(1) Acoustic history When a tree in the forest collapses, a loud sound is heard, but no one is in this virgin forest, so this sound is not heard. Is this a sound coming out? The sound is definitely coming out, because when the trunk and branches touch the ground, they all produce some sound, but no one hears it, but the sound is heard by humans or other animals. It is different, so this is the psychology (Psychoacoustics).
The acoustic principle I am talking about here is mainly to let a tuner understand all aspects of acoustics, not acoustic research, or acoustics of master's and doctoral degrees, so the acoustic theory I have covered in this book is It can actually be used by people who operate the sound on site.
In 1915, an American named E. S. Pidham put a telephony listener on the horn of a record disc, and the sound was given to a group of people celebrating Christmas in San Francisco. Electroacoustics was born. After the end of the First World War, at the inauguration of President Harding in the United States, Bell Company connected the phone's dynamic listening device to the horn of the record player at that time, and was able to pass the voice to the president. A large group of people at the ceremony, so many professional audio research and the development of sound reinforcement engineering. Sound researchers are not only trying to improve audio equipment, but also doing various experiments to understand human response to hearing. But the most advanced audio research people understand that sound science is a holistic study. To understand every aspect of audio equipment and human physiological response to hearing, they have made great contributions in the past years and now. As early as 1877, Sir Raleigh of the United Kingdom had already done acoustic research. He once said: "All problems, whether directly or indirectly related to sound, must be decided with our ears because it It is our organ of hearing, and the decision of the ear should be the final decision. It is no longer necessary to accept the appeal. But this does not mean that all audio research is done by the ear alone. When we find that the foundation of the sound is a When we detect the phenomenon of physics, we must turn to another area of ​​physics. It is physics. The important rate can be studied from this aspect, and our hearing sense must accept these rates." It can be seen from the above paragraph that even in the absence of electroacoustic sound generation, older scientists believe that this is the realm of physics.
The famous scientist, Lord Calvin of the United Kingdom, often said: "When you measure what you say and can express it with numbers, you have some knowledge of it. But if you can't express it with numbers, then your Knowledge is still rudimentary and imperfect; for anything, this may be the source of knowledge, but your mind has not yet reached the realm of science.†Lord Calvin (1824—1907) was the best of the 19th century. One of the scientists, in order to commemorate the great man, the absolute temperature - 273.16 degrees Celsius is named 0 degrees Calvin.
Don & Carolyn Davis is the author of the book Sound System Engineering. Known as the Acoustic Bible, this book is almost a must-read for every foreign research sound. I quote this passage in his book: "The knowledge of mathematics and physics is a necessary condition for understanding sound engineering in essence. The deeper the understanding of these two kinds of science, the more you can cross the feelings that you get from feelings, The use of science to cite the facts. The famous audiophile James Moore once said: 'In sound science, anything that seems obvious on the surface is usually wrong.'
I quoted the instructions of several scientists and audiologists above, mainly because most of the people who do audio today are of course interested in sound and music, but think that they can identify what is right by their hearing. Good or bad sound, I don't understand that this is a professional engineering knowledge, it is not good sound. Sir Lai Li, who was far away from the 19th century, has pointed out that this is a scientific realm. Modern sound engineering is also working hard like other scientific academics, so acoustic engineering is inseparable from mathematics and physics.
(2) The live sound and the sound of the studio are separately operated in the live sound here. It has many different places from the recording technology. Many people think that the highest level of sound is the recording technology. This is not comprehensive. of. In the recording technology, basically there is no feedback, because when operating in a recording studio, all the peripheral factors can be controlled, but in the live audio replay, we can not avoid many live audio problems. So live audio and recording audio are two different kinds of learning. The requirements for live audio and studio audio are different, so there are many different devices. For example, in the mixing console used in the recording studio, each input has a plurality of parameter equalization, so that the sound engineer can finely adjust the input source of each input as much as possible to achieve the best sound source effect. A mixer for live audio, usually in each of its inputs, the balance is relatively simple. Because many times, the live tuner does not have a lot of time to fine-tune the sound source of each channel. In addition, the volume control fader of each channel in the live sound mixer can not only attenuate the volume, but also Can gain 10-14 dB. If you are working on a mixing studio for the studio, this putter does not need to be used for a lot of time, so the English name of this putter is fader, which means the attenuator. For high-power amplifiers used in live audio, they all have fans for cooling purposes, because live audio amplifiers often work at maximum power output, and there are many times when you are doing live sound outdoors, the surrounding temperature may be quite high. If you are in the studio, there will usually be air conditioning, the temperature will of course not be too high, and the amplifier in the recording studio is mainly used to push the monitor speakers. Of course, there is no need to output a large amount of power, so the amplifier only needs to use ordinary The heat sink can dissipate very little heat. If the amplifier is equipped with a fan, the sound from the fan will cause noise, so the amplifier in the recording room basically does not need a fan.
The speakers used in live audio, in order to spread a large sound pressure to the audience at a long distance, so they need to be very efficient, but the monitor speakers used in the recording studio are used by the sound engineer to monitor the sound source or The final result of the recording, the sound engineer is sitting close to the monitor speakers to monitor, so the monitor is a near-field speaker, does not require high sensitivity, the effect is completely different from the live audio speakers.
(3) The relationship between audio and wavelength Many live tuners do not care about the relationship between audio and wavelength. In fact, this is very important: audio and wavelength have a direct relationship with the speed of sound. At an altitude of air pressure, at a temperature of 21 degrees Celsius, the sound speed is 344m / s, and I contact domestic tuner, their usual sound speed is 34Om / s, this is the speed of the sound at 15 degrees Celsius, but The main thing to remember is that the speed of the sound changes with the air temperature and air pressure. The lower the temperature, the higher the molecular density in the air, so the speed of the sound will decrease, and if it is done at a high altitude. Sound, because the air pressure is reduced, the molecules in the air become scarce, and the sound speed increases. The relationship between audio and wavelength and sound is: wavelength = sound speed / frequency; λ = v / f, if the sound speed is assumed to be 344 m / s, the wavelength of 100Hz audio is 3.44 m, the wavelength of 1000hz (ie lkHz) It is 34.4 cm, and a 20 kHz audio wavelength is 1.7 cm.
(4) High, medium and low frequency of the speaker. For example, we now have an 18-hour cone speaker unit, which is installed in a wood-made speaker. The panel area of ​​this speaker is 1 square meter, which is the height of the panel. And the width is l meters. How do we calculate the high, medium and low frequencies of this speaker? First we have to calculate the diagonal length of the speaker panel, which is the square root of 2 = 1.414m, and the l/4 wavelength of any frequency is more than 1.414m. For this speaker it is low frequency; if the l/4 wavelength of a frequency is 1.414m, the wavelength is 4×1.414m= 5.656m, this frequency=344m/s÷5.656m=60.8/ s = 60.8 Hz, so any audio below 60.8 Hz is its low frequency for this speaker. When the frequency of 60.8 Hz or lower is transmitted from this speaker, their diffusion image is spherical, which is equal to the volume of these frequencies before and after the speaker and above and below when we hang the speaker in the middle of a room. The sound pressure emitted is almost the same, and the sound that is released becomes non-directional. When the l/4 wavelength of a certain frequency is smaller than the diagonal length of the speaker panel, but this wavelength is greater than the radius of the speaker, this frequency is the medium frequency of the speaker. For example, we now use an 18-hour unit with a radius of 9 inches, which is 22.86cm=0.2286m. This audio is 344m/s÷0.2286m=1505Hz. The frequency from 60.8Hz to 1505HZ is the medium frequency of this speaker. . The shape in which the medium frequency is diffused from the speaker is hemispherical. That is, if we release this frequency from the speaker that was hung in the center of the room, the shape of the sound diffusing from the speaker panel is hemispherical. Behind the speaker is the sound that does not hear this frequency. The frequency of 1505Hz and higher is its high frequency for this speaker. The shape of the sound that is diffused from the speaker at a high frequency is tapered, and the higher the frequency, the narrower the shape of the cone. Usually, if the frequency exceeds 4 times of the start of high audio, the shape of the sound will slowly become a straight line without spreading. If it is not sitting in the position of the alignment unit, these high frequencies will not be heard. Therefore, if many high-frequency units are paper cone type, the diameter of the paper cone is very small, and the high-frequency lower limit of the speaker is increased as much as possible, and it is desirable to increase the width of the high-frequency diffusion. We often see tweeters in home audio speakers, usually with a 1-2 cell or a hemispherical unit, for this reason. The tweeter of the professional live sound, because it has to emit a large high-frequency sound pressure, it must be treated with a horn.
(5) Different kinds of sound fields When a cone speaker receives the signal from the power amplifier, the paper cone will shake forward and backward. When the paper cone advances, the paper cone hits the air molecules in front of it. The air in front of the cone increases the pressure, and the molecules continue to push forward, colliding with the air molecules in front of them, causing a slight high pressure. When the cone is retreating, the air molecules in front of the cone create a slight vacuum, and then the molecules follow the cone back, causing a slight pressure drop in the air. But let's not forget that the air is elastic, but the air in front of the cone is just shaken by the action of the cone, and it cannot reach the elasticity of the air itself. At this time we have to look at the wavelength of this frequency, the sound is to leave until When the distance of the paper cone is 2.5 times the wavelength, the air exerts the elasticity of the sound. For example, a 100Hz frequency, its wavelength is 3.44 meters, so the sound is about 2.5 × 3.44 meters = 8.6 meters away from the paper cone, is the true 100Hz sound. If 10OHz is used, the distance from the paper cone is less than 8.6 meters, which is the near sound field of lOOHz, and more than 8.6 meters is the far sound field of 100Hz. Why do we need to understand the far and near sound field? Many times the electric bass player in a band, he often does not understand the effect of the near sound field, and on his electric bass speaker, there is an equalization knob is written Bass is the title of this musician. The electric bass player usually stands in a place not far from the electric bass speaker. If he stands in the near sound field, sometimes he feels that the bass is not enough, he will adjust the Bass equalization knob as much as possible, but the audience is Their position will hear very strong bass, and often cause bad results. These strong basses will also run into the singer's microphone. If the tuner feels that the singer's voice is not enough, he will improve the singer's voice, but at the same time, the electric bass will also increase the volume. The sound has encountered difficulties. The lowest E string of the electric bass is 41Hz, but because the pickup is placed at the end of the string, the first harmonic of the 41hz 82Hz is the main electric bass low frequency, and the 82Hz wavelength is 4.2m (344m/s). Divided by 82/s = 4.195m), so about 10 meters away from the electric bass speaker is the 82Hz far sound field, and because the electric bass player does not stand so far away from his speaker, The sound he heard was only the near sound field, not the sound heard by the audience. So when we talk about the far and near sound field of the speaker, the most important thing is to notice the frequency and its wavelength, instead of simply looking at how far away from the speaker is equal to the far or near sound field, the most important thing is to remember when we listen to music, To be in the far field, not in the near sound field.
(6) Direct sound field, reflected sound field, and non-direct sound field. When the speaker makes a sound in a room, the listener can hear the sound directly from the speaker. This is the direct sound field (indirectfield), but it can also be heard. The sound reflected from walls, ceilings and floors is called the reverberant field. The more the direct sound field is heard by the audience, the smaller the sound of the reflected sound field is, the better the sound is, because the sound of the direct sound field is controllable, but the sound of the reflected sound field is uncontrollable, only The sound from the direct breeding field will be dyed to reduce the clarity of the original sound, so the listener who is closer to the speaker will feel a better sound, and the audience sitting behind is likely It is the reflected sound field sound that they hear is louder than the direct sound field sound, the sound effect will be worse and the clarity will be reduced. Sometimes when a band plays on the stage, because they don’t have a monitor, and the main speakers on both sides are placed close to the mouth, the sounds heard by the band and the singer are not completely from the direct sound field. The position of standing is called the direct sound field, and the sound effect is certainly not good. This will also affect the performance level of the band, and the audience will not hear the sound of the performance.
(7) Interface Interference When we choose to place the speaker, it is important to note that the sound from the speaker is affected by the interface next to it. For example, the main speakers placed on both sides of the table, their bass cones off the ground and the wall next to it, if it is about 1 meter, a 4 meter wavelength audio will be interfered by these two interfaces. A frequency of 4 meters is 86Hz (344m / s ÷ 4m = 86Hz), when the sound of 86HZ is released from the speaker, the large air pressure just hits the ground and the wall within 1/4 weeks, and then l/4 The week is reflected back in front of the cone of the speaker, but this time the cone is retreating. The large air pressure reflected from the ground and the wall will be offset by the backlash of the cone, causing the loss of important bass. If this happens, you should move the speaker back to the table 0.5-1 meters, so that the sound from the speaker can't directly hit the ground, and if you can move the speaker to the wall near the two sides, you can use the wall. The reflection system makes a louder volume. 80-100Hz This frequency is very important. It is the resonance point of our lung space and the resonance frequency of the bass drum. If it is because the interface is not understood, the position where the speaker is placed is wrong. It is really not worth it. .
(8) High and low bass effects It is difficult for us to specify a certain frequency above the high pitch or below a certain frequency. We often say that the human hearing is from 20Hh-20KHz, but the frequency of 20kHz is rarely heard by people. Usually Only young people under the age of 20 can only be heard if their ears are not damaged. If you do an auditory test, the highest listening frequency is only 8 kHz. When the sound is transmitted, the high frequency is much faster than the low frequency attenuation. If you compare 1 kHz with 10 kHz, when the sound ran 100 meters, the 10 kHz 'frequency will attenuate 30-35 dB compared to the I kHz volume. (See Figure 1) High frequency sounds are more directional than low frequencies. After the high-frequency sound comes out of the unit, if it is blocked by the object, the high-pitched sound can no longer be transmitted. This is very different from the low frequency, because the high-frequency wavelength is relatively short, and it will not be blocked by the object. Turning, but the low-frequency wavelength is relatively long, so many times even if an object is blocked in the front, the low frequency can also turn. For example, some professional speakers are designed to put a high horn in front of its woofer, but for the low frequency emitted by this woofer, it simply can't see what is blocking the sound in front, so low frequency It can be passed on as usual. From our auditory point of view, we need to hear high-frequency sounds to distinguish different types of sounds, but if we simply talk about people's conversations, we only need to hear the frequency of 4kHz and below, we can immediately identify What is the person talking. For example, the voice transmission of the phone, the high frequency only reaches 4 kHz, so sometimes when a person who has not talked to you for a long time, when he calls you, just say "Hey!", you can immediately identify him. You haven’t heard the voice of a friend for a long time. We listen to high frequencies and have directionality, that is, we can identify the direction of high frequency sound sources. Because the high-frequency sound has passed to our two ears, there is already a very small time difference, so when they come to the ear, there are different phase changes. Can we identify this by changing the phase?
(1) Acoustic history When a tree in the forest collapses, a loud sound is heard, but no one is in this virgin forest, so this sound is not heard. Is this a sound coming out? The sound is definitely coming out, because when the trunk and branches touch the ground, they all produce some sound, but no one hears it, but the sound is heard by humans or other animals. It is different, so this is the psychology (Psychoacoustics).
The acoustic principle I am talking about here is mainly to let a tuner understand all aspects of acoustics, not acoustic research, or acoustics of master's and doctoral degrees, so the acoustic theory I have covered in this book is It can actually be used by people who operate the sound on site.
In 1915, an American named E. S. Pidham put a telephony listener on the horn of a record disc, and the sound was given to a group of people celebrating Christmas in San Francisco. Electroacoustics was born. After the end of the First World War, at the inauguration of President Harding in the United States, Bell Company connected the phone's dynamic listening device to the horn of the record player at that time, and was able to pass the voice to the president. A large group of people at the ceremony, so many professional audio research and the development of sound reinforcement engineering. Sound researchers are not only trying to improve audio equipment, but also doing various experiments to understand human response to hearing. But the most advanced audio research people understand that sound science is a holistic study. To understand every aspect of audio equipment and human physiological response to hearing, they have made great contributions in the past years and now. As early as 1877, Sir Raleigh of the United Kingdom had already done acoustic research. He once said: "All problems, whether directly or indirectly related to sound, must be decided with our ears because it It is our organ of hearing, and the decision of the ear should be the final decision. It is no longer necessary to accept the appeal. But this does not mean that all audio research is done by the ear alone. When we find that the foundation of the sound is a When we detect the phenomenon of physics, we must turn to another area of ​​physics. It is physics. The important rate can be studied from this aspect, and our hearing sense must accept these rates." It can be seen from the above paragraph that even in the absence of electroacoustic sound generation, older scientists believe that this is the realm of physics.
The famous scientist, Lord Calvin of the United Kingdom, often said: "When you measure what you say and can express it with numbers, you have some knowledge of it. But if you can't express it with numbers, then your Knowledge is still rudimentary and imperfect; for anything, this may be the source of knowledge, but your mind has not yet reached the realm of science.†Lord Calvin (1824—1907) was the best of the 19th century. One of the scientists, in order to commemorate the great man, the absolute temperature - 273.16 degrees Celsius is named 0 degrees Calvin.
Don & Carolyn Davis is the author of the book Sound System Engineering. Known as the Acoustic Bible, this book is almost a must-read for every foreign research sound. I quote this passage in his book: "The knowledge of mathematics and physics is a necessary condition for understanding sound engineering in essence. The deeper the understanding of these two kinds of science, the more you can cross the feelings that you get from feelings, The use of science to cite the facts. The famous audiophile James Moore once said: 'In sound science, anything that seems obvious on the surface is usually wrong.'
I quoted the instructions of several scientists and audiologists above, mainly because most of the people who do audio today are of course interested in sound and music, but think that they can identify what is right by their hearing. Good or bad sound, I don't understand that this is a professional engineering knowledge, it is not good sound. Sir Lai Li, who was far away from the 19th century, has pointed out that this is a scientific realm. Modern sound engineering is also working hard like other scientific academics, so acoustic engineering is inseparable from mathematics and physics.
(2) The live sound and the sound of the studio are separately operated in the live sound here. It has many different places from the recording technology. Many people think that the highest level of sound is the recording technology. This is not comprehensive. of. In the recording technology, basically there is no feedback, because when operating in a recording studio, all the peripheral factors can be controlled, but in the live audio replay, we can not avoid many live audio problems. So live audio and recording audio are two different kinds of learning. The requirements for live audio and studio audio are different, so there are many different devices. For example, in the mixing console used in the recording studio, each input has a plurality of parameter equalization, so that the sound engineer can finely adjust the input source of each input as much as possible to achieve the best sound source effect. A mixer for live audio, usually in each of its inputs, the balance is relatively simple. Because many times, the live tuner does not have a lot of time to fine-tune the sound source of each channel. In addition, the volume control fader of each channel in the live sound mixer can not only attenuate the volume, but also Can gain 10-14 dB. If you are working on a mixing studio for the studio, this putter does not need to be used for a lot of time, so the English name of this putter is fader, which means the attenuator. For high-power amplifiers used in live audio, they all have fans for cooling purposes, because live audio amplifiers often work at maximum power output, and there are many times when you are doing live sound outdoors, the surrounding temperature may be quite high. If you are in the studio, there will usually be air conditioning, the temperature will of course not be too high, and the amplifier in the recording studio is mainly used to push the monitor speakers. Of course, there is no need to output a large amount of power, so the amplifier only needs to use ordinary The heat sink can dissipate very little heat. If the amplifier is equipped with a fan, the sound from the fan will cause noise, so the amplifier in the recording room basically does not need a fan.
The speakers used in live audio, in order to spread a large sound pressure to the audience at a long distance, so they need to be very efficient, but the monitor speakers used in the recording studio are used by the sound engineer to monitor the sound source or The final result of the recording, the sound engineer is sitting close to the monitor speakers to monitor, so the monitor is a near-field speaker, does not require high sensitivity, the effect is completely different from the live audio speakers.
(3) The relationship between audio and wavelength Many live tuners do not care about the relationship between audio and wavelength. In fact, this is very important: audio and wavelength have a direct relationship with the speed of sound. At an altitude of air pressure, at a temperature of 21 degrees Celsius, the sound speed is 344m / s, and I contact domestic tuner, their usual sound speed is 34Om / s, this is the speed of the sound at 15 degrees Celsius, but The main thing to remember is that the speed of the sound changes with the air temperature and air pressure. The lower the temperature, the higher the molecular density in the air, so the speed of the sound will decrease, and if it is done at a high altitude. Sound, because the air pressure is reduced, the molecules in the air become scarce, and the sound speed increases. The relationship between audio and wavelength and sound is: wavelength = sound speed / frequency; λ = v / f, if the sound speed is assumed to be 344 m / s, the wavelength of 100Hz audio is 3.44 m, the wavelength of 1000hz (ie lkHz) It is 34.4 cm, and a 20 kHz audio wavelength is 1.7 cm.
(4) High, medium and low frequency of the speaker. For example, we now have an 18-hour cone speaker unit, which is installed in a wood-made speaker. The panel area of ​​this speaker is 1 square meter, which is the height of the panel. And the width is l meters. How do we calculate the high, medium and low frequencies of this speaker? First we have to calculate the diagonal length of the speaker panel, which is the square root of 2 = 1.414m, and the l/4 wavelength of any frequency is more than 1.414m. For this speaker it is low frequency; if the l/4 wavelength of a frequency is 1.414m, the wavelength is 4×1.414m= 5.656m, this frequency=344m/s÷5.656m=60.8/ s = 60.8 Hz, so any audio below 60.8 Hz is its low frequency for this speaker. When the frequency of 60.8 Hz or lower is transmitted from this speaker, their diffusion image is spherical, which is equal to the volume of these frequencies before and after the speaker and above and below when we hang the speaker in the middle of a room. The sound pressure emitted is almost the same, and the sound that is released becomes non-directional. When the l/4 wavelength of a certain frequency is smaller than the diagonal length of the speaker panel, but this wavelength is greater than the radius of the speaker, this frequency is the medium frequency of the speaker. For example, we now use an 18-hour unit with a radius of 9 inches, which is 22.86cm=0.2286m. This audio is 344m/s÷0.2286m=1505Hz. The frequency from 60.8Hz to 1505HZ is the medium frequency of this speaker. . The shape in which the medium frequency is diffused from the speaker is hemispherical. That is, if we release this frequency from the speaker that was hung in the center of the room, the shape of the sound diffusing from the speaker panel is hemispherical. Behind the speaker is the sound that does not hear this frequency. The frequency of 1505Hz and higher is its high frequency for this speaker. The shape of the sound that is diffused from the speaker at a high frequency is tapered, and the higher the frequency, the narrower the shape of the cone. Usually, if the frequency exceeds 4 times of the start of high audio, the shape of the sound will slowly become a straight line without spreading. If it is not sitting in the position of the alignment unit, these high frequencies will not be heard. Therefore, if many high-frequency units are paper cone type, the diameter of the paper cone is very small, and the high-frequency lower limit of the speaker is increased as much as possible, and it is desirable to increase the width of the high-frequency diffusion. We often see tweeters in home audio speakers, usually with a 1-2 cell or a hemispherical unit, for this reason. The tweeter of the professional live sound, because it has to emit a large high-frequency sound pressure, it must be treated with a horn.
(5) Different kinds of sound fields When a cone speaker receives the signal from the power amplifier, the paper cone will shake forward and backward. When the paper cone advances, the paper cone hits the air molecules in front of it. The air in front of the cone increases the pressure, and the molecules continue to push forward, colliding with the air molecules in front of them, causing a slight high pressure. When the cone is retreating, the air molecules in front of the cone create a slight vacuum, and then the molecules follow the cone back, causing a slight pressure drop in the air. But let's not forget that the air is elastic, but the air in front of the cone is just shaken by the action of the cone, and it cannot reach the elasticity of the air itself. At this time we have to look at the wavelength of this frequency, the sound is to leave until When the distance of the paper cone is 2.5 times the wavelength, the air exerts the elasticity of the sound. For example, a 100Hz frequency, its wavelength is 3.44 meters, so the sound is about 2.5 × 3.44 meters = 8.6 meters away from the paper cone, is the true 100Hz sound. If 10OHz is used, the distance from the paper cone is less than 8.6 meters, which is the near sound field of lOOHz, and more than 8.6 meters is the far sound field of 100Hz. Why do we need to understand the far and near sound field? Many times the electric bass player in a band, he often does not understand the effect of the near sound field, and on his electric bass speaker, there is an equalization knob is written Bass is the title of this musician. The electric bass player usually stands in a place not far from the electric bass speaker. If he stands in the near sound field, sometimes he feels that the bass is not enough, he will adjust the Bass equalization knob as much as possible, but the audience is Their position will hear very strong bass, and often cause bad results. These strong basses will also run into the singer's microphone. If the tuner feels that the singer's voice is not enough, he will improve the singer's voice, but at the same time, the electric bass will also increase the volume. The sound has encountered difficulties. The lowest E string of the electric bass is 41Hz, but because the pickup is placed at the end of the string, the first harmonic of the 41hz 82Hz is the main electric bass low frequency, and the 82Hz wavelength is 4.2m (344m/s). Divided by 82/s = 4.195m), so about 10 meters away from the electric bass speaker is the 82Hz far sound field, and because the electric bass player does not stand so far away from his speaker, The sound he heard was only the near sound field, not the sound heard by the audience. So when we talk about the far and near sound field of the speaker, the most important thing is to notice the frequency and its wavelength, instead of simply looking at how far away from the speaker is equal to the far or near sound field, the most important thing is to remember when we listen to music, To be in the far field, not in the near sound field.
(6) Direct sound field, reflected sound field, and non-direct sound field. When the speaker makes a sound in a room, the listener can hear the sound directly from the speaker. This is the direct sound field (indirectfield), but it can also be heard. The sound reflected from walls, ceilings and floors is called the reverberant field. The more the direct sound field is heard by the audience, the smaller the sound of the reflected sound field is, the better the sound is, because the sound of the direct sound field is controllable, but the sound of the reflected sound field is uncontrollable, only The sound from the direct breeding field will be dyed to reduce the clarity of the original sound, so the listener who is closer to the speaker will feel a better sound, and the audience sitting behind is likely It is the reflected sound field sound that they hear is louder than the direct sound field sound, the sound effect will be worse and the clarity will be reduced. Sometimes when a band plays on the stage, because they don’t have a monitor, and the main speakers on both sides are placed close to the mouth, the sounds heard by the band and the singer are not completely from the direct sound field. The position of standing is called the direct sound field, and the sound effect is certainly not good. This will also affect the performance level of the band, and the audience will not hear the sound of the performance.
(7) Interface Interference When we choose to place the speaker, it is important to note that the sound from the speaker is affected by the interface next to it. For example, the main speakers placed on both sides of the table, their bass cones off the ground and the wall next to it, if it is about 1 meter, a 4 meter wavelength audio will be interfered by these two interfaces. A frequency of 4 meters is 86Hz (344m / s ÷ 4m = 86Hz), when the sound of 86HZ is released from the speaker, the large air pressure just hits the ground and the wall within 1/4 weeks, and then l/4周就å射回到音箱的纸盆é¢å‰ï¼Œä½†è¿™ä¸ªæ—¶å€™åˆšå·§çº¸ç›†è¦åŽé€€ï¼ŒåŽŸæ¥ä»Žåœ°é¢åŠå¢™å£å射过æ¥çš„大空气压力就会被纸盆åŽé€€çš„åŠ¨ä½œæŠµæ¶ˆå¾ˆå¤šï¼Œé€ æˆå¤±åŽ»äº†å¾ˆé‡è¦çš„低音。如果é‡åˆ°è¿™ä¸ªæƒ…况，就应该把音箱å‘å°åŽé€€0．5ï¼1米，让音箱所å‘出æ¥çš„声音ä¸èƒ½ç›´æŽ¥å°„到地é¢ä¸Šï¼Œè€Œå¦‚æžœå¯ä»¥æŠŠéŸ³ç®±ç§»åˆ°é 近两边的墙å£æ—¶ï¼Œæ›´å¯åˆ©ç”¨å¢™å£çš„å射制åšå‡ºæ›´å¤§çš„音é‡ã€‚ 80-100Hz 这段频率是很é‡è¦çš„ï¼Œå®ƒæ˜¯æˆ‘ä»¬è‚ºéƒ¨ç©ºé—´çš„å…±é¸£ç‚¹ï¼Œä¹Ÿæ˜¯ä½ŽéŸ³é¼“çš„å…±é¸£é¢‘çŽ‡ï¼Œå¦‚æžœæ˜¯å› ä¸ºä¸äº†è§£ç•Œé¢å¹²æ‰°è€Œæ‘†é”™äº†éŸ³ç®±æ”¾ç½®çš„ä½ç½®ï¼Œå®žåœ¨æ˜¯å¾ˆä¸å€¼å¾—的。
（8）高ã€ä½ŽéŸ³æ•ˆæžœæˆ‘们很难指定æŸä¸€é¢‘率以上为高音或æŸé¢‘率以下为低音，我们常常说人的å¬è§‰æ˜¯ä»Ž20Hhï¼20KHz，但20kHz的频率是很少人能够å¬åˆ°çš„，通常åªæœ‰20å²ä»¥ä¸‹çš„é’年人，他们的耳朵没有å—到任何的æŸåæ—¶æ‰å¯ä»¥å¬å¾—到。如果åšå¬è§‰æµ‹éªŒï¼Œæœ€é«˜çš„测å¬é¢‘率åªæ˜¯8 kHzã€‚å½“å£°éŸ³ä¼ å‡ºåŽ»æ—¶ï¼Œé«˜é¢‘çŽ‡æ˜¯æ¯”ä½Žé¢‘çŽ‡è¡°å‡å¿«å¾—多，如果用1kHzè·Ÿ10kHzåšæ¯”较时，当声音跑了100ç±³åŽï¼Œ10kHzçš„'频率比起IkHz的音é‡ä¼šè¡°å‡30ï¼35dB的。（请å‚看图①）比起低频率，高频率声音是比较有方å‘性的。高频率的声音从å•å…ƒè·‘了出æ¥åŽï¼Œå¦‚æžœå—到物体的阻挡，高音就ä¸èƒ½å†ä¼ 过去，这个是跟低频率有很大的ä¸åŒï¼Œå› 为高频率的波长是比较çŸï¼Œå—到物体阻挡之åŽä¸ä¼šè½¬å¼¯ï¼Œä½†ä½Žé¢‘率的波长是比较长，所以很多时候就算有物体在å‰é¢é˜»æŒ¡ï¼Œä½Žé¢‘率也å¯ä»¥è½¬å¼¯è¿‡åŽ»ã€‚例如有些专业音箱的设计是把一个高音å·è§’放在它的低音å•å…ƒå‰é¢ï¼Œä½†å¯¹è¿™ä¸ªä½ŽéŸ³å•å…ƒæ‰€å‘出æ¥çš„ä½Žé¢‘çŽ‡ï¼Œå®ƒæ ¹æœ¬å°±çœ‹ä¸åˆ°å‰é¢æ˜¯æœ‰ä»€ä¹ˆä¸œè¥¿é˜»æŒ¡å£°éŸ³ä¼¼çš„，所以低频率å¯ä»¥ç…§æ ·ä¼ 过去。 从我们的å¬è§‰ä¸Šæ¥è¯´ï¼Œæˆ‘们是需è¦å¬åˆ°é«˜é¢‘率的声音æ¥è¾¨åˆ«å„ç±»ä¸åŒçš„声音，但如果å•çº¯æ˜¯è®²äººçš„è°ˆè¯å£°æ—¶ï¼Œæˆ‘们åªéœ€è¦å¬åˆ°4kHzåŠä»¥ä¸‹çš„频率，就能马上辨别是什么人在说è¯ã€‚例如电è¯çš„å£°éŸ³ä¼ é€ï¼Œé«˜é¢‘åªè¾¾åˆ°4kHzï¼Œæ‰€ä»¥æœ‰æ—¶å€™å½“ä¸€ä¸ªå¾ˆä¹…éƒ½æ²¡æœ‰å’Œä½ è°ˆè¯çš„人，当他打电è¯ç»™ä½ 时，åªè¦è¯´ï¼šâ€œå–‚ï¼â€ï¼Œä½ 就马上便å¯ä»¥é‰´åˆ«ä»–æ˜¯ä½ å¾ˆä¹…éƒ½æ²¡æœ‰è°ˆè¿‡è¯çš„朋å‹çš„声音。我们å¬é«˜é¢‘也有方å‘性，å³æ˜¯æˆ‘们能够辨别高频声音æ¥æºçš„æ–¹å‘ã€‚å› ä¸ºé«˜é¢‘çš„å£°éŸ³ä¼ åˆ°æˆ‘ä»¬ä¸¤ä¸ªè€³æœµæ—¶ï¼Œå·²ç»æœ‰äº†å¾ˆç»†å¾®çš„时间差，所以它们æ¥åˆ°è€³æœµçš„时候有ä¸åŒçš„相ä½æ”¹å˜ï¼Œæˆ‘们就借ç€è¿™æ”¹å˜äº†çš„相ä½å¯ä»¥é‰´å®š?
(1)声å¦åŽ†å²å½“森林ä¸æœ‰ä¸€æ£µæ ‘倒塌下æ¥æ—¶ï¼Œå‘出一阵轰然大å“声音，但是没有人在这个原始森林ä¸ï¼Œæ‰€ä»¥å°±å¬ä¸åˆ°è¿™å£°éŸ³ã€‚这算ä¸ç®—有声音å‘出æ¥å‘¢?声音是肯定å‘出æ¥äº†ï¼Œå› ä¸ºå½“æ ‘å¹²åŠæ ‘æžæŽ¥è§¦åœ°é¢æ—¶ï¼Œå®ƒä»¬éƒ½ä¼šäº§ç”ŸæŸäº›å£°éŸ³ï¼Œä½†æ˜¯æ²¡æœ‰äººå¬è§ï¼Œä½†è¿™å£°éŸ³å¯¹äºŽäººç±»æˆ–其他动物所å¬åˆ°çš„是有所ä¸åŒï¼Œæ‰€ä»¥è¿™å°±æ˜¯å£°å¦ä¸Šæ‰€è¯´çš„心ç†(Psychoacoustics)。
我在这里讲的声å¦åŽŸç†ï¼Œæœ€ä¸»è¦æ˜¯è®©ä¸€ä¸ªè°ƒéŸ³å‘˜èƒ½å¤Ÿäº†è§£å£°å¦çš„å„æ–¹é¢ï¼Œè€Œä¸æ˜¯è¿›è¡Œå£°å¦ç ”究，或是硕士ã€åšå£«çš„声å¦è®ºæ–‡ï¼Œæ‰€ä»¥æˆ‘在这书内讲的声å¦ç†è®ºéƒ½æ˜¯å®žé™…å¯ä»¥ç»™åœ¨çŽ°åœºæ“作音å“的人用得上的。
1915年，有一个美国人åå«E． S． Pridham将一个当时的电è¯æ”¶å¬å™¨å¥—在一个æ’放唱片音å“çš„å·è§’上，而声音å¯ä»¥ç»™ä¸€ç¾¤åœ¨æ—§é‡‘山市庆ç¥åœ£è¯žçš„群众å¬æ—¶ï¼Œç”µå£°å¦å°±è¯žç”Ÿäº†ã€‚当第一次世界大战结æŸä¹‹åŽï¼Œåœ¨ç¾Žå›½å“ˆå®šæ€»ç»Ÿ(Harding)å°±èŒå…¸ç¤¼ä¸Šï¼Œç¾Žå›½è´å°”å…¬å¸æŠŠç”µè¯çš„动圈收å¬å™¨è¿žæŽ¥åœ¨å½“时的唱片唱机的å·è§’ä¸Šï¼Œå°±èƒ½å¤ŸæŠŠå£°éŸ³ä¼ ç»™è§‚çœ‹æ€»ç»Ÿå°±èŒå…¸ç¤¼çš„ä¸€å¤§ç¾¤ç¾¤ä¼—ï¼Œå› æ¤å°±äº§ç”Ÿäº†å¾ˆå¤šä¸“业的音å“ç ”ç©¶åŠå¼€å‘了扩声工程这门å¦é—®ã€‚音å“ç ”ç©¶äººå‘˜ä¸å•çº¯æ˜¯åŠªåŠ›åœ°æŠŠéŸ³å“器æ进行改进，也åšäº†å„ç±»ä¸åŒçš„实验æ¥äº†è§£äººç±»å¯¹å¬è§‰çš„å应。但最高级的音å“ç ”ç©¶äººåŒéƒ½æ˜Žç™½éŸ³å“å¦æ˜¯è¦æ•´ä½“çš„ç ”ç©¶ï¼Œè¦äº†è§£éŸ³å“器æçš„æ¯ä¸€ä¸ªçŽ¯èŠ‚，åŠäººç±»å¯¹å¬è§‰çš„生ç†å应，他们在过去多年内直至现在都作出了很大的贡献。早在1877年，英国的莱æŽçˆµå£«(Lord Raleigh)就已ç»åšè¿‡å£°å¦çš„ç ”ç©¶ï¼Œä»–æ›¾ç»è¯´è¿‡ï¼šâ€œæ‰€æœ‰ä¸è®ºç›´æŽ¥æˆ–间接有关音å“的问题，一定è¦ç”¨æˆ‘们的耳朵æ¥åšå†³å®šï¼Œå› 为它是我们的å¬è§‰çš„器官，而耳朵的决定就应该算是最åŽå†³å®šï¼Œæ˜¯ä¸éœ€è¦å†æŽ¥å—上诉的。但这ä¸æ˜¯ç‰äºŽæ‰€æœ‰çš„音å“ç ”ç©¶éƒ½æ˜¯å•é 用耳朵æ¥è¿›è¡Œã€‚当我们å‘çŽ°å£°éŸ³çš„æ ¹åŸºæ˜¯ä¸€ä¸ªç‰©ç†çš„现象时，我们探测这个音å“境界就è¦è½¬åˆ°å¦å¤–一个领域范围，它就是物ç†å¦ã€‚é‡è¦çš„定率是å¯ä»¥ä»Žç ”究这方é¢è€Œæ¥ï¼Œè€Œæˆ‘们的å¬è§‰æ„Ÿåº”也一定è¦æŽ¥å—这些定率。â€æˆ‘们å¯ä»¥ä»Žä»¥ä¸Šä¸€æ®µæ–‡å—看到，就算在没有电声音å“å¦äº§ç”Ÿçš„时候，è€å‰è¾ˆç§‘å¦å®¶éƒ½è®¤ä¸ºè¿™ä¸ªæ˜¯ç‰©ç†çš„领域。
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戴维斯夫妇(Don＆ Carolyn Davis)是《音å“系统工程》(Sound System Engineering)这本书的作者。这书被称为音å“圣ç»ï¼Œå‡ 乎是æ¯ä¸€ä¸ªå¤–å›½ç ”ç©¶éŸ³å“的人必读之物。我引述他书内这一段：“具有数å¦å’Œç‰©ç†å¦çš„知识，是实质上了解音å“工程å¦çš„å¿…è¦æ¡ä»¶ã€‚对这两ç§ç§‘å¦è®¤è¯†è¶Šæ·±ï¼Œè¶Šèƒ½ä½¿ä½ 跨越从感觉上所得到的æ„念，而达到用科å¦æ¥å¼•è¯äº‹å®žã€‚ç€å音å“家å 士摩亚曾ç»è¯´è¿‡ï¼š'在音å“å¦ä¸ï¼Œä»»ä½•åœ¨è¡¨é¢çœ‹æ¥å¾ˆæ˜Žæ˜¾çš„事情，通常都是错误的'。â€
æˆ‘åœ¨ä»¥ä¸Šå¼•è¿°äº†å‡ ä½ç§‘å¦å®¶åŠéŸ³å“å¦å®¶çš„è®è¨€ï¼Œä¸»è¦æ˜¯å› 为现在大部分åšéŸ³å“的人士，他们当然是对音å“åŠéŸ³ä¹å¾ˆæœ‰å…´è¶£ï¼Œä½†æ˜¯ä»¥ä¸ºå…‰é 他们的å¬è§‰å°±å¯ä»¥é‰´å®šä»€ä¹ˆæ˜¯å¥½æˆ–ä¸å¥½çš„音å“，ä¸æ˜Žç™½è¿™æ˜¯ä¸€é—¨ä¸“业的工程å¦é—®ï¼Œæ˜¯åšä¸å¥½éŸ³å“的。远在19世纪的莱æŽçˆµå£«å·²ç»æŒ‡å‡ºè¿™æ˜¯ä¸€ä¸ªç§‘å¦çš„境界，现代的音å“工程å¦ä¹Ÿåƒå…¶å®ƒç§‘å¦å¦æœ¯ä¸€æ ·æ£åœ¨åŠªåŠ›åœ°å‘展，所以音å“工程å¦æ˜¯ç¦»ä¸å¼€æ•°å¦åŠç‰©ç†å¦çš„。
(2)现场音晌与录音室音晌的分别在这里所讲解的现场音å“地æ“作，它与录音技术是有很多ä¸åŒçš„地方，有很多人以为音å“的最高境界就是录音技术，这是ä¸å…¨é¢çš„。在录音技术上，基本是没有碰到åé¦ˆçš„æƒ…å†µï¼Œå› ä¸ºåœ¨ä¸€ä¸ªå½•éŸ³å®¤å†…è¿›è¡Œæ“ä½œæ—¶ï¼Œæ‰€æœ‰çš„å¤–å›´å› æ•°éƒ½å¯ä»¥å¾—到控制，但是在现场音å“é‡æ’时，我们是ä¸å¯ä»¥é¿å…有很多现场音å“的问题，所以现场音å“和录音音å“是两ç§ä¸åŒçš„å¦é—®ã€‚现场音å“跟录音室音å“çš„è¦æ±‚是ä¸åŒçš„，所以有很多器æ也是ä¸åŒçš„。例如在录音室内所用的调音å°ï¼Œå®ƒä»¬çš„æ¯è·¯è¾“入都有多个å‚æ•°å‡è¡¡ï¼Œè®©å½•éŸ³å¸ˆå¯ä»¥æŠŠæ¯è·¯è¾“入的音æºå°½é‡åšæœ€ç²¾å¯†åœ°å¾®è°ƒï¼ŒåŠ¡æ±‚达到最好的音æºæ•ˆæžœã€‚ A mixer for live audio, usually in each of its inputs, the balance is relatively simple.å› ä¸ºå¾ˆå¤šæ—¶å€™ï¼ŒçŽ°åœºè°ƒéŸ³å¸ˆæ ¹æœ¬å°±æ²¡æœ‰å¾ˆå¤šæ—¶é—´æŠŠæ¯è·¯çš„音æºåšå¾ˆä»”细地微调，而在现场音å“的调音å°æ¯è·¯çš„音é‡æŽ§åˆ¶æŽ¨æ†ï¼Œå®ƒä»¬é™¤äº†å¯ä»¥æŠŠéŸ³é‡åšè¡°å‡å¤–，也å¯ä»¥å¢žç›Š10—14 dB。 If you are working on a mixing studio for the studio, this putter does not need to be used for a lot of time, so the English name of this putter is fader, which means the attenuator. For high-power amplifiers used in live audio, they all have fans for cooling purposes, because live audio amplifiers often work at maximum power output, and there are many times when you are doing live sound outdoors, the surrounding temperature may be quite high. If you are in the studio, there will usually be air conditioning, the temperature will of course not be too high, and the amplifier in the recording studio is mainly used to push the monitor speakers. Of course, there is no need to output a large amount of power, so the amplifier only needs to use ordinary The heat sink can dissipate very little heat.如果功放装有风扇的è¯ï¼Œé£Žæ‰‡å‘出æ¥çš„声音åè€Œé€ æˆå™ªéŸ³ï¼Œæ‰€ä»¥åœ¨å½•éŸ³å®¤å†…的功放基本上是ä¸éœ€è¦é£Žæ‰‡çš„。
现场音å“所用的音箱，为ç€è¦æŠŠå¾ˆå¤§çš„å£°åŽ‹ä¼ æ’绘在远è·ç¦»çš„观众，所以它们是需è¦å¾ˆé«˜æ•ˆçŽ‡çš„，但在录音室内所用的监å¬éŸ³ç®±ï¼Œæ˜¯å½•éŸ³å¸ˆç”¨æ¥ç›‘å¬å£°æºæˆ–录音的最åŽç»“果，录音师是å在è·ç›‘å¬éŸ³ç®±å¾ˆè¿‘的地方æ¥ç›‘å¬ï¼Œæ‰€ä»¥ç›‘å¬éŸ³ç®±æ˜¯ä¸€ç§è¿‘音场的音箱，ä¸éœ€è¦é«˜çµæ•åº¦ï¼Œä½œç”¨è·ŸçŽ°åœºéŸ³å“音箱是完全ä¸åŒçš„。
(3)音频与波长的关系很多现场调音师都没有ç†ä¼šåˆ°éŸ³é¢‘与波长的关系，其实这是很é‡è¦çš„：音频åŠæ³¢é•¿ä¸Žå£°éŸ³çš„速度是有直接的关系。在海拔空气压力下，21æ‘„æ°æ¸©åº¦æ—¶ï¼Œå£°éŸ³é€Ÿåº¦ä¸º344mï¼s，而我接触国内的调音师，他们常用的声音速度是34Omï¼s，这个是在15æ‘„æ°åº¦çš„温度时声音的速度，但大家最主è¦è®°å¾—就是声音的速度会éšç€ç©ºæ°”温度åŠç©ºæ°”压力而改å˜çš„，温度越低，空气里的分å密度就会增高，所以声音的速度就会下é™ï¼Œè€Œå¦‚果在高海拔的地方åšçŽ°åœºéŸ³å“ï¼Œå› ä¸ºç©ºæ°”åŽ‹åŠ›å‡å°‘，空气内的分åå˜å¾—ç¨€å°‘ï¼Œå£°éŸ³é€Ÿåº¦å°±ä¼šå¢žåŠ ã€‚éŸ³é¢‘åŠæ³¢é•¿ä¸Žå£°éŸ³çš„关系是：波长=声音速度ï¼é¢‘率； λ=vï¼f，如果å‡å®šéŸ³é€Ÿæ˜¯344 mï¼s时，100Hz的音频的波长就是3．44 m，1000hz(å³lkHz)的波长就是34．4 cm，而一个20kHz的音频波长为1．7cm。
(4)音箱的高ã€ä¸ã€ä½Žé¢‘率例如我们现在有一个18时的纸盆扬声器å•å…ƒï¼Œè£…置在一个用木æé€ çš„éŸ³ç®±å†…ï¼Œè€Œè¿™éŸ³ç®±çš„é¢æ¿é¢ç§¯æ˜¯l平方米，å³è¿™é¢æ¿çš„高度åŠå®½åº¦å‡æ˜¯lç±³ã€‚æˆ‘ä»¬æ€Žæ ·è®¡ç®—è¿™éŸ³ç®±çš„é«˜ã€ä¸ã€ä½Žé¢‘率呢?首先我们è¦è®¡ç®—这音箱é¢æ¿çš„对角长度，是2çš„æ–¹æ ¹=1．414m，任何频率的lï¼4波长是超过1．414m时，对这音箱æ¥è¯´å®ƒå°±æ˜¯ä½Žé¢‘；如果一个频率的lï¼4波长是1．414m时，波长就是4×1．414m= 5．656m，这频率=344mï¼s÷5．656m=60．8ï¼s=60．8Hz，所以任何音频低于60．8Hz时，对这音箱æ¥è¯´å°±æ˜¯å®ƒçš„低频率。当60．8Hzæˆ–æ›´ä½Žçš„é¢‘çŽ‡ä»Žè¿™éŸ³ç®±ä¼ æ’出æ¥æ—¶ï¼Œå®ƒä»¬çš„扩散形象是çƒåž‹çš„，ç‰äºŽå¦‚果我们把这音箱悬挂在一个房间ä¸é—´æ—¶ï¼Œè¿™äº›é¢‘率的音é‡åœ¨éŸ³ç®±çš„å‰åŽå·¦å³åŠä¸Šä¸‹æ‰€å‘出æ¥çš„声压都是差ä¸å¤šçš„，放出æ¥çš„声音å˜æˆæ²¡æœ‰æ–¹å‘性。当æŸé¢‘率的lï¼4波长是å°äºŽéŸ³ç®±é¢æ¿çš„对角长度，但这波长åˆå¤§äºŽæ‰¬å£°å™¨çš„åŠå¾„时，这段频率就是这音箱的ä¸é¢‘率。例如我们现在是用一个18æ—¶å•å…ƒï¼Œè¿™å•å…ƒçš„åŠå¾„为9寸，就是22.86cm=0.2286m,这个音频为344m/s÷0．2286m=1505Hz,从60.8Hz-1505HZ频就是这音箱的ä¸é¢‘率。ä¸é¢‘率从这音箱所扩散出æ¥çš„形状是åŠçƒå½¢çš„，å³å¦‚果我们把这段频率从刚æ‰æ‚¬æŒ‚在房间ä¸å¿ƒçš„音箱放出æ¥æ—¶ï¼Œå£°éŸ³ä»ŽéŸ³ç®±é¢æ¿æ‰©æ•£å‡ºæ¥çš„形状是åŠçƒå½¢ã€‚在音箱åŽé¢æ˜¯å¬ä¸åˆ°è¿™æ®µé¢‘率的声音。1505HzåŠæ›´é«˜çš„频率，对这音箱æ¥è¯´å°±æ˜¯å®ƒçš„高频率。高频率从音箱扩散出æ¥çš„声音形状是锥形的，频率越高，锥的形状越窄。通常如果频率超过开始高音频的4å€æ—¶ï¼Œå£°éŸ³æ‰©æ•£å‡ºæ¥çš„形状会慢慢å˜æˆä¸€æ¡ç›´çº¿è€Œä¸æ‰©æ•£ï¼Œå¦‚æžœä¸æ˜¯å在对æ£å•å…ƒçš„ä½ç½®ï¼Œå°±å¬ä¸åˆ°è¿™äº›é«˜é¢‘率。所以很多高频率å•å…ƒå¦‚果是纸盆型的è¯ï¼Œè¿™çº¸ç›†çš„直径是很å°çš„，把这音箱的高频下é™å°½é‡æé«˜ï¼Œå¸Œæœ›èƒ½å¤Ÿä½¿é«˜é¢‘æ‰©æ•£çš„å®½åº¦å¢žåŠ ã€‚æˆ‘ä»¬å¸¸å¸¸è§åˆ°å®¶åºéŸ³å“音箱ä¸çš„高音å•å…ƒï¼Œé€šå¸¸ä¼šç”¨l—2时的纸盆å•å…ƒï¼Œæˆ–åŠçƒçŠ¶çš„å•å…ƒï¼Œç†ç”±å°±æ˜¯è¿™ä¸ªåŽŸå› 。而专业现场音å“的高音å•å…ƒï¼Œå› 为è¦å‘出很大的高频声压，所以说一定是采用å·è§’处ç†çš„。
(5)å„ç±»ä¸åŒçš„音场当一个纸盆扬声器接å—äº†ä»ŽåŠŸæ”¾ä¼ è¿‡æ¥çš„ä¿¡å·åŽï¼Œçº¸ç›†å°±ä¼šä½œå‡ºå‰åŽçš„摇动，当纸盆å‘å‰æŽ¨è¿›æ—¶ï¼Œçº¸ç›†æ’žå‡»åˆ°å®ƒå‰é¢çš„空气分å，在纸盆å‰é¢çš„ç©ºæ°”å°±ä¼šå¢žåŠ åŽ‹åŠ›ï¼Œè¿™äº›åˆ†å就会继ç»å‘å‰æŽ¨è¿›ï¼Œç¢°æ’žå®ƒä»¬å‰é¢çš„空气分åï¼Œé€ æˆè½»å¾®çš„高气压。当纸盆å‘åŽé€€æ—¶ï¼Œçº¸ç›†å‰é¢çš„空气分å就会产生轻微的真空，然åŽè¿™äº›åˆ†å会跟ç€çº¸ç›†çš„åŽé€€ï¼Œé€ æˆè¿™é‡Œçš„空气有轻微的压力å‡å°‘。但我们ä¸è¦å¿˜è®°ï¼Œç©ºæ°”是有弹力的，但在纸盆å‰é¢çš„空气是刚刚被纸盆的动作摇动，ä¸èƒ½è¾¾åˆ°ç©ºæ°”本身的弹力，这时我们便è¦çœ‹è¿™é¢‘率的波长，声音是è¦ç›´åˆ°ç¦»å¼€çº¸ç›†çš„è·ç¦»æœ‰2．5å€æ³¢é•¿æ—¶ï¼Œè¿™äº›ç©ºæ°”æ‰å‘æŒ¥å‡ºé€ æˆå£°éŸ³çš„弹力。例如一个100Hz的频率，它的波长是3．44米，所以声音è¦ç¦»å¼€çº¸ç›†2．5×3．44ç±³=8．6米之外，æ‰æ˜¯çœŸæ£çš„这个100Hz的声音。如果用10OHzæ¥ç®—，离开纸盆的è·ç¦»è¿˜æ²¡è¾¾åˆ°8．6米就为lOOHz的近音场，而超过8．6ç±³æ‰æ˜¯100Hz的远音场。为什么我们è¦äº†è§£è¿œè¿‘音场呢?很多时候在一队ä¹é˜Ÿä¸çš„电è´å¸æ‰‹ï¼Œä»–往往都ä¸äº†è§£è¿‘音场的效果，而在他的电è´å¸éŸ³ç®±ä¸Šï¼Œæœ‰ä¸€ä¸ªå‡è¡¡æ—‹é’®å°±æ˜¯å†™ç€è´å¸ï¼ˆBass) ，æ£æ˜¯è¿™ä¹æ‰‹çš„称å·ã€‚电è´å¸æ‰‹é€šå¸¸ä¼šç«™åœ¨ç¦»å¼€ç”µè´å¸éŸ³ç®±ä¸è¿œçš„地方åšæ¼”å¥ï¼Œå¦‚果他站在近音场时，有时会觉得低音ä¸è¶³ï¼Œå°±ä¼šæŠŠè¿™Bassçš„å‡è¡¡æ—‹é’®å°½é‡è°ƒå¤§ï¼Œä½†å¬ä¼—在他们的ä½ç½®å°±ä¼šå¬å¾—åˆ°å¾ˆå¼ºçƒˆçš„ä½ŽéŸ³ï¼Œå¾ˆå¤šæ—¶å€™é€ æˆä¸å¥½çš„效果。这些强烈的低音也会跑进æŒæ‰‹çš„è¯ç’ï¼Œå¦‚æžœè°ƒéŸ³å¸ˆå› ä¸ºè§‰å¾—æŒæ‰‹çš„声音ä¸è¶³å¤Ÿæ—¶ï¼Œå°±ä¼šæŠŠæŒæ‰‹è¿™ä¸€è·¯çš„声音æ高，但也åŒæ—¶æŠŠç”µè´å¸çš„低音é‡ä¹Ÿæ高了，调音就é‡ä¸Šäº†å›°éš¾ã€‚电è´å¸çš„最低E弦是41Hzï¼Œä½†å› ä¸ºæ‹¾éŸ³å™¨æ˜¯æ”¾åœ¨å¼¦çš„æœ«æ®µï¼Œæ‰€ä»¥41hz第一个è°éŸ³82Hzæ‰æ˜¯ä¸»è¦çš„电è´å¸ä½Žé¢‘率，82Hz的波长是4．2米（344mï¼s 除以82ï¼s=4.195m），所以差ä¸å¤šè¦ç¦»å¼€ç”µè´å¸éŸ³ç®±10米左å³æ‰æ˜¯è¿™82Hzçš„è¿œéŸ³åœºï¼Œè€Œå› ä¸ºç”µè´å¸æ‰‹ä¸ä¼šç«™åˆ°ç¦»å¼€ä»–的音箱这么远的è·ç¦»æ—¶ï¼Œä»–å¬åˆ°çš„声音åªæ˜¯è¿‘音场，而ä¸æ˜¯å¬ä¼—所å¬å¾—到的声音。所以我们当说到扬声器的远近音场时，最主è¦æ˜¯æ³¨æ„到频率åŠå®ƒçš„波长，而ä¸æ˜¯å•çº¯çœ‹ç¦»å¼€éŸ³ç®±å¤šè¿œå°±æ˜¯ç‰äºŽè¿œæˆ–近音场，最主è¦å°±æ˜¯è®°å¾—我们当欣èµéŸ³ä¹æ—¶ï¼Œæ˜¯è¦åœ¨è¿œéŸ³åœºçš„ä½ç½®ï¼Œè€Œä¸æ˜¯åœ¨è¿‘音场的ä½ç½®ã€‚
（6）直接音场ã€å射音场ã€ä¸ç›´æŽ¥éŸ³åœºå½“扬声器在一个房间内å‘出声音，å¬ä¼—å¯ä»¥å¬åˆ°ç›´æŽ¥ä»Žæ‰¬å£°å™¨ä¼ 过æ¥çš„声音，这就是直接音场（indirectfield），但也å¯ä»¥å¬åˆ°ä»Žå¢™ã€å¤©èŠ±æ¿åŠåœ°æ¿æ‰€å射过æ¥çš„声音，这就å«åšå射音场（reverberant field)。å¬ä¼—å¬åˆ°è¶Šå¤šçš„直接音场的声音，å射音场的声音就越å°æ—¶ï¼Œè¿™å£°éŸ³å°±è¶Šå¥½ï¼Œå› 为直接音场的声音是å¯ä»¥æŽ§åˆ¶çš„，但å射音场的声音是ä¸èƒ½æŽ§åˆ¶çš„，åªä¼šæŠŠç›´æŽ¥è‚²åœºå‘出æ¥çš„å£°éŸ³åŠ ä¸Šå–§æŸ“ï¼ŒæŠŠåŽŸæœ¬å£°éŸ³çš„æ¸…æ™°åº¦åº•å‡ä½Žï¼Œæ‰€ä»¥å得离音箱比较近的å¬ä¼—就会感觉到好一点的音å“效果，而å在åŽé¢çš„å¬ä¼—很å¯èƒ½æ˜¯ä»–们å¬åˆ°çš„å射音场声音比直接音场声音更大，音å“效果便会比较差åŠæ¸…晰度é™ä½Žã€‚有时候一队ä¹é˜Ÿåœ¨å°ä¸Šæ¼”å‡ºæ—¶ï¼Œå› ä¸ºä»–ä»¬æ²¡æœ‰ç›‘å¬éŸ³ç®±ï¼Œè€Œä¸¤æ—的主音箱是放在é è¿‘å°å£çš„ä½ç½®ï¼Œä¹é˜ŸåŠæŒæ‰‹æ‰€å¬åˆ°çš„声音完全没有从直接音场放过æ¥çš„，他们站立的ä½ç½®å°±å«åšä¸ç›´æŽ¥éŸ³åœºï¼Œå£°éŸ³æ•ˆæžœå½“然ä¸ä¼šå¥½ï¼Œè¿™ä¹Ÿä¼šå½±å“到ä¹é˜Ÿçš„表演水平，令观众å¬åˆ°ä¸å¤ªå¥½çš„演出声音。
（7）界é¢å¹²æ‰°å½“我们选择放置音箱的ä½ç½®æ—¶ï¼Œå¾ˆé‡è¦çš„一环是è¦æ³¨æ„到音箱所å‘出æ¥çš„声音是会å—到它æ—边的界é¢å½±å“è€Œé€ æˆå¹²æ‰°ã€‚例如放在å°å£ä¸¤æ—的主音箱，它们的低音纸盆离开地é¢åŠæ—边的墙å£å¦‚果是大约在1米的时候，一个4米波长的音频就会å—到这两个界é¢çš„干扰。一个4米波长的频率是86Hz（344mï¼s ÷ 4mï¼ 86Hz），当86HZ的声音从音箱放出æ¥æ—¶ï¼Œå¤§çš„空气压力在1ï¼4周内刚巧碰到地é¢åŠå¢™å£ï¼Œå†è¿‡lï¼4周就å射回到音箱的纸盆é¢å‰ï¼Œä½†è¿™ä¸ªæ—¶å€™åˆšå·§çº¸ç›†è¦åŽé€€ï¼ŒåŽŸæ¥ä»Žåœ°é¢åŠå¢™å£å射过æ¥çš„大空气压力就会被纸盆åŽé€€çš„åŠ¨ä½œæŠµæ¶ˆå¾ˆå¤šï¼Œé€ æˆå¤±åŽ»äº†å¾ˆé‡è¦çš„低音。如果é‡åˆ°è¿™ä¸ªæƒ…况，就应该把音箱å‘å°åŽé€€0．5ï¼1米，让音箱所å‘出æ¥çš„声音ä¸èƒ½ç›´æŽ¥å°„到地é¢ä¸Šï¼Œè€Œå¦‚æžœå¯ä»¥æŠŠéŸ³ç®±ç§»åˆ°é 近两边的墙å£æ—¶ï¼Œæ›´å¯åˆ©ç”¨å¢™å£çš„å射制åšå‡ºæ›´å¤§çš„音é‡ã€‚80-100Hz 这段频率是很é‡è¦çš„ï¼Œå®ƒæ˜¯æˆ‘ä»¬è‚ºéƒ¨ç©ºé—´çš„å…±é¸£ç‚¹ï¼Œä¹Ÿæ˜¯ä½ŽéŸ³é¼“çš„å…±é¸£é¢‘çŽ‡ï¼Œå¦‚æžœæ˜¯å› ä¸ºä¸äº†è§£ç•Œé¢å¹²æ‰°è€Œæ‘†é”™äº†éŸ³ç®±æ”¾ç½®çš„ä½ç½®ï¼Œå®žåœ¨æ˜¯å¾ˆä¸å€¼å¾—的。
（8）高ã€ä½ŽéŸ³æ•ˆæžœæˆ‘们很难指定æŸä¸€é¢‘率以上为高音或æŸé¢‘率以下为低音，我们常常说人的å¬è§‰æ˜¯ä»Ž20Hhï¼20KHz，但20kHz的频率是很少人能够å¬åˆ°çš„，通常åªæœ‰20å²ä»¥ä¸‹çš„é’年人，他们的耳朵没有å—到任何的æŸåæ—¶æ‰å¯ä»¥å¬å¾—到。如果åšå¬è§‰æµ‹éªŒï¼Œæœ€é«˜çš„测å¬é¢‘率åªæ˜¯8 kHzã€‚å½“å£°éŸ³ä¼ å‡ºåŽ»æ—¶ï¼Œé«˜é¢‘çŽ‡æ˜¯æ¯”ä½Žé¢‘çŽ‡è¡°å‡å¿«å¾—多，如果用1kHzè·Ÿ10kHzåšæ¯”较时，当声音跑了100ç±³åŽï¼Œ10kHzçš„'频率比起IkHz的音é‡ä¼šè¡°å‡30ï¼35dB的。（请å‚看图①）比起低频率，高频率声音是比较有方å‘性的。高频率的声音从å•å…ƒè·‘了出æ¥åŽï¼Œå¦‚æžœå—到物体的阻挡，高音就ä¸èƒ½å†ä¼ 过去，这个是跟低频率有很大的ä¸åŒï¼Œå› 为高频率的波长是比较çŸï¼Œå—到物体阻挡之åŽä¸ä¼šè½¬å¼¯ï¼Œä½†ä½Žé¢‘率的波长是比较长，所以很多时候就算有物体在å‰é¢é˜»æŒ¡ï¼Œä½Žé¢‘率也å¯ä»¥è½¬å¼¯è¿‡åŽ»ã€‚例如有些专业音箱的设计是把一个高音å·è§’放在它的低音å•å…ƒå‰é¢ï¼Œä½†å¯¹è¿™ä¸ªä½ŽéŸ³å•å…ƒæ‰€å‘出æ¥çš„ä½Žé¢‘çŽ‡ï¼Œå®ƒæ ¹æœ¬å°±çœ‹ä¸åˆ°å‰é¢æ˜¯æœ‰ä»€ä¹ˆä¸œè¥¿é˜»æŒ¡å£°éŸ³ä¼¼çš„，所以低频率å¯ä»¥ç…§æ ·ä¼ 过去。 从我们的å¬è§‰ä¸Šæ¥è¯´ï¼Œæˆ‘们是需è¦å¬åˆ°é«˜é¢‘率的声音æ¥è¾¨åˆ«å„ç±»ä¸åŒçš„声音，但如果å•çº¯æ˜¯è®²äººçš„è°ˆè¯å£°æ—¶ï¼Œæˆ‘们åªéœ€è¦å¬åˆ°4kHzåŠä»¥ä¸‹çš„频率，就能马上辨别是什么人在说è¯ã€‚例如电è¯çš„å£°éŸ³ä¼ é€ï¼Œé«˜é¢‘åªè¾¾åˆ°4kHzï¼Œæ‰€ä»¥æœ‰æ—¶å€™å½“ä¸€ä¸ªå¾ˆä¹…éƒ½æ²¡æœ‰å’Œä½ è°ˆè¯çš„人，当他打电è¯ç»™ä½ 时，åªè¦è¯´ï¼šâ€œå–‚ï¼â€ï¼Œä½ 就马上便å¯ä»¥é‰´åˆ«ä»–æ˜¯ä½ å¾ˆä¹…éƒ½æ²¡æœ‰è°ˆè¿‡è¯çš„朋å‹çš„声音。我们å¬é«˜é¢‘也有方å‘性，å³æ˜¯æˆ‘们能够辨别高频声音æ¥æºçš„æ–¹å‘ã€‚å› ä¸ºé«˜é¢‘çš„å£°éŸ³ä¼ åˆ°æˆ‘ä»¬ä¸¤ä¸ªè€³æœµæ—¶ï¼Œå·²ç»æœ‰äº†å¾ˆç»†å¾®çš„时间差，所以它们æ¥åˆ°è€³æœµçš„时候有ä¸åŒçš„相ä½æ”¹å˜ï¼Œæˆ‘们就借ç€è¿™æ”¹å˜äº†çš„相ä½å¯ä»¥é‰´å®š?
The acoustic principle I am talking about here is mainly to let a tuner understand all aspects of acoustics, not acoustic research, or acoustics of master's and doctoral degrees, so the acoustic theory I have covered in this book is It can actually be used by people who operate the sound on site.
In 1915, an American named E. S. Pidham put a telephony listener on the horn of a record disc, and the sound was given to a group of people celebrating Christmas in San Francisco. Electroacoustics was born. After the end of the First World War, at the inauguration of President Harding in the United States, Bell Company connected the phone's dynamic listening device to the horn of the record player at that time, and was able to pass the voice to the president. A large group of people at the ceremony, so many professional audio research and the development of sound reinforcement engineering. Sound researchers are not only trying to improve audio equipment, but also doing various experiments to understand human response to hearing. But the most advanced audio research people understand that sound science is a holistic study. To understand every aspect of audio equipment and human physiological response to hearing, they have made great contributions in the past years and now. As early as 1877, Sir Raleigh of the United Kingdom had already done acoustic research. He once said: "All problems, whether directly or indirectly related to sound, must be decided with our ears because it It is our organ of hearing, and the decision of the ear should be the final decision. It is no longer necessary to accept the appeal. But this does not mean that all audio research is done by the ear alone. When we find that the foundation of the sound is a When we detect the phenomenon of physics, we must turn to another area of ​​physics. It is physics. The important rate can be studied from this aspect, and our hearing sense must accept these rates." It can be seen from the above paragraph that even in the absence of electroacoustic sound generation, older scientists believe that this is the realm of physics.
The famous scientist, Lord Calvin of the United Kingdom, often said: "When you measure what you say and can express it with numbers, you have some knowledge of it. But if you can't express it with numbers, then your Knowledge is still rudimentary and imperfect; for anything, this may be the source of knowledge, but your mind has not yet reached the realm of science.†Lord Calvin (1824—1907) was the best of the 19th century. One of the scientists, in order to commemorate the great man, the absolute temperature - 273.16 degrees Celsius is named 0 degrees Calvin.
Don & Carolyn Davis is the author of the book Sound System Engineering. Known as the Acoustic Bible, this book is almost a must-read for every foreign research sound. I quote this passage in his book: "The knowledge of mathematics and physics is a necessary condition for understanding sound engineering in essence. The deeper the understanding of these two kinds of science, the more you can cross the feelings that you get from feelings, The use of science to cite the facts. The famous audiophile James Moore once said: 'In sound science, anything that seems obvious on the surface is usually wrong.'
I quoted the instructions of several scientists and audiologists above, mainly because most of the people who do audio today are of course interested in sound and music, but think that they can identify what is right by their hearing. Good or bad sound, I don't understand that this is a professional engineering knowledge, it is not good sound. Sir Lai Li, who was far away from the 19th century, has pointed out that this is a scientific realm. Modern sound engineering is also working hard like other scientific academics, so acoustic engineering is inseparable from mathematics and physics.
(2) The live sound and the sound of the studio are separately operated in the live sound here. It has many different places from the recording technology. Many people think that the highest level of sound is the recording technology. This is not comprehensive. of. In the recording technology, basically there is no feedback, because when operating in a recording studio, all the peripheral factors can be controlled, but in the live audio replay, we can not avoid many live audio problems. So live audio and recording audio are two different kinds of learning. The requirements for live audio and studio audio are different, so there are many different devices. For example, in the mixing console used in the recording studio, each input has a plurality of parameter equalization, so that the sound engineer can finely adjust the input source of each input as much as possible to achieve the best sound source effect. A mixer for live audio, usually in each of its inputs, the balance is relatively simple. Because many times, the live tuner does not have a lot of time to fine-tune the sound source of each channel. In addition, the volume control fader of each channel in the live sound mixer can not only attenuate the volume, but also Can gain 10-14 dB. If you are working on a mixing studio for the studio, this putter does not need to be used for a lot of time, so the English name of this putter is fader, which means the attenuator. For high-power amplifiers used in live audio, they all have fans for cooling purposes, because live audio amplifiers often work at maximum power output, and there are many times when you are doing live sound outdoors, the surrounding temperature may be quite high. If you are in the studio, there will usually be air conditioning, the temperature will of course not be too high, and the amplifier in the recording studio is mainly used to push the monitor speakers. Of course, there is no need to output a large amount of power, so the amplifier only needs to use ordinary The heat sink can dissipate very little heat. If the amplifier is equipped with a fan, the sound from the fan will cause noise, so the amplifier in the recording room basically does not need a fan.
The speakers used in live audio, in order to spread a large sound pressure to the audience at a long distance, so they need to be very efficient, but the monitor speakers used in the recording studio are used by the sound engineer to monitor the sound source or The final result of the recording, the sound engineer is sitting close to the monitor speakers to monitor, so the monitor is a near-field speaker, does not require high sensitivity, the effect is completely different from the live audio speakers.
(3) The relationship between audio and wavelength Many live tuners do not care about the relationship between audio and wavelength. In fact, this is very important: audio and wavelength have a direct relationship with the speed of sound. At an altitude of air pressure, at a temperature of 21 degrees Celsius, the sound speed is 344m / s, and I contact domestic tuner, their usual sound speed is 34Om / s, this is the speed of the sound at 15 degrees Celsius, but The main thing to remember is that the speed of the sound changes with the air temperature and air pressure. The lower the temperature, the higher the molecular density in the air, so the speed of the sound will decrease, and if it is done at a high altitude. Sound, because the air pressure is reduced, the molecules in the air become scarce, and the sound speed increases. The relationship between audio and wavelength and sound is: wavelength = sound speed / frequency; λ = v / f, if the sound speed is assumed to be 344 m / s, the wavelength of 100Hz audio is 3.44 m, the wavelength of 1000hz (ie lkHz) It is 34.4 cm, and a 20 kHz audio wavelength is 1.7 cm.
(4) High, medium and low frequency of the speaker. For example, we now have an 18-hour cone speaker unit, which is installed in a wood-made speaker. The panel area of ​​this speaker is 1 square meter, which is the height of the panel. And the width is l meters. How do we calculate the high, medium and low frequencies of this speaker? First we have to calculate the diagonal length of the speaker panel, which is the square root of 2 = 1.414m, and the l/4 wavelength of any frequency is more than 1.414m. For this speaker it is low frequency; if the l/4 wavelength of a frequency is 1.414m, the wavelength is 4×1.414m= 5.656m, this frequency=344m/s÷5.656m=60.8/ s = 60.8 Hz, so any audio below 60.8 Hz is its low frequency for this speaker. When the frequency of 60.8 Hz or lower is transmitted from this speaker, their diffusion image is spherical, which is equal to the volume of these frequencies before and after the speaker and above and below when we hang the speaker in the middle of a room. The sound pressure emitted is almost the same, and the sound that is released becomes non-directional. When the l/4 wavelength of a certain frequency is smaller than the diagonal length of the speaker panel, but this wavelength is greater than the radius of the speaker, this frequency is the medium frequency of the speaker. For example, we now use an 18-hour unit with a radius of 9 inches, which is 22.86cm=0.2286m. This audio is 344m/s÷0.2286m=1505Hz. The frequency from 60.8Hz to 1505HZ is the medium frequency of this speaker. . The shape in which the medium frequency is diffused from the speaker is hemispherical. That is, if we release this frequency from the speaker that was hung in the center of the room, the shape of the sound diffusing from the speaker panel is hemispherical. Behind the speaker is the sound that does not hear this frequency. The frequency of 1505Hz and higher is its high frequency for this speaker. The shape of the sound that is diffused from the speaker at a high frequency is tapered, and the higher the frequency, the narrower the shape of the cone. Usually, if the frequency exceeds 4 times of the start of high audio, the shape of the sound will slowly become a straight line without spreading. If it is not sitting in the position of the alignment unit, these high frequencies will not be heard. Therefore, if many high-frequency units are paper cone type, the diameter of the paper cone is very small, and the high-frequency lower limit of the speaker is increased as much as possible, and it is desirable to increase the width of the high-frequency diffusion. We often see tweeters in home audio speakers, usually with a 1-2 cell or a hemispherical unit, for this reason. The tweeter of the professional live sound, because it has to emit a large high-frequency sound pressure, it must be treated with a horn.
(5) Different kinds of sound fields When a cone speaker receives the signal from the power amplifier, the paper cone will shake forward and backward. When the paper cone advances, the paper cone hits the air molecules in front of it. The air in front of the cone increases the pressure, and the molecules continue to push forward, colliding with the air molecules in front of them, causing a slight high pressure. When the cone is retreating, the air molecules in front of the cone create a slight vacuum, and then the molecules follow the cone back, causing a slight pressure drop in the air. But let's not forget that the air is elastic, but the air in front of the cone is just shaken by the action of the cone, and it cannot reach the elasticity of the air itself. At this time we have to look at the wavelength of this frequency, the sound is to leave until When the distance of the paper cone is 2.5 times the wavelength, the air exerts the elasticity of the sound. For example, a 100Hz frequency, its wavelength is 3.44 meters, so the sound is about 2.5 × 3.44 meters = 8.6 meters away from the paper cone, is the true 100Hz sound. If 10OHz is used, the distance from the paper cone is less than 8.6 meters, which is the near sound field of lOOHz, and more than 8.6 meters is the far sound field of 100Hz. Why do we need to understand the far and near sound field? Many times the electric bass player in a band, he often does not understand the effect of the near sound field, and on his electric bass speaker, there is an equalization knob is written Bass is the title of this musician. The electric bass player usually stands in a place not far from the electric bass speaker. If he stands in the near sound field, sometimes he feels that the bass is not enough, he will adjust the Bass equalization knob as much as possible, but the audience is Their position will hear very strong bass, and often cause bad results. These strong basses will also run into the singer's microphone. If the tuner feels that the singer's voice is not enough, he will improve the singer's voice, but at the same time, the electric bass will also increase the volume. The sound has encountered difficulties. The lowest E string of the electric bass is 41Hz, but because the pickup is placed at the end of the string, the first harmonic of the 41hz 82Hz is the main electric bass low frequency, and the 82Hz wavelength is 4.2m (344m/s). Divided by 82/s = 4.195m), so about 10 meters away from the electric bass speaker is the 82Hz far sound field, and because the electric bass player does not stand so far away from his speaker, The sound he heard was only the near sound field, not the sound heard by the audience. So when we talk about the far and near sound field of the speaker, the most important thing is to notice the frequency and its wavelength, instead of simply looking at how far away from the speaker is equal to the far or near sound field, the most important thing is to remember when we listen to music, To be in the far field, not in the near sound field.
(6) Direct sound field, reflected sound field, and non-direct sound field. When the speaker makes a sound in a room, the listener can hear the sound directly from the speaker. This is the direct sound field (indirectfield), but it can also be heard. The sound reflected from walls, ceilings and floors is called the reverberant field. The more the direct sound field is heard by the audience, the smaller the sound of the reflected sound field is, the better the sound is, because the sound of the direct sound field is controllable, but the sound of the reflected sound field is uncontrollable, only The sound from the direct breeding field will be dyed to reduce the clarity of the original sound, so the listener who is closer to the speaker will feel a better sound, and the audience sitting behind is likely It is the reflected sound field sound that they hear is louder than the direct sound field sound, the sound effect will be worse and the clarity will be reduced. Sometimes when a band plays on the stage, because they don’t have a monitor, and the main speakers on both sides are placed close to the mouth, the sounds heard by the band and the singer are not completely from the direct sound field. The position of standing is called the direct sound field, and the sound effect is certainly not good. This will also affect the performance level of the band, and the audience will not hear the sound of the performance.
(7) Interface Interference When we choose to place the speaker, it is important to note that the sound from the speaker is affected by the interface next to it. For example, the main speakers placed on both sides of the table, their bass cones off the ground and the wall next to it, if it is about 1 meter, a 4 meter wavelength audio will be interfered by these two interfaces. A frequency of 4 meters is 86Hz (344m / s ÷ 4m = 86Hz), when the sound of 86HZ is released from the speaker, the large air pressure just hits the ground and the wall within 1/4 weeks, and then l/4 The week is reflected back in front of the cone of the speaker, but this time the cone is retreating. The large air pressure reflected from the ground and the wall will be offset by the backlash of the cone, causing the loss of important bass. If this happens, you should move the speaker back to the table 0.5-1 meters, so that the sound from the speaker can't directly hit the ground, and if you can move the speaker to the wall near the two sides, you can use the wall. The reflection system makes a louder volume. 80-100Hz This frequency is very important. It is the resonance point of our lung space and the resonance frequency of the bass drum. If it is because the interface is not understood, the position where the speaker is placed is wrong. It is really not worth it. .
(8) High and low bass effects It is difficult for us to specify a certain frequency above the high pitch or below a certain frequency. We often say that the human hearing is from 20Hh-20KHz, but the frequency of 20kHz is rarely heard by people. Usually Only young people under the age of 20 can only be heard if their ears are not damaged. If you do an auditory test, the highest listening frequency is only 8 kHz. When the sound is transmitted, the high frequency is much faster than the low frequency attenuation. If you compare 1 kHz with 10 kHz, when the sound ran 100 meters, the 10 kHz 'frequency will attenuate 30-35 dB compared to the I kHz volume. (See Figure 1) High frequency sounds are more directional than low frequencies. After the high-frequency sound comes out of the unit, if it is blocked by the object, the high-pitched sound can no longer be transmitted. This is very different from the low frequency, because the high-frequency wavelength is relatively short, and it will not be blocked by the object. Turning, but the low-frequency wavelength is relatively long, so many times even if an object is blocked in the front, the low frequency can also turn. For example, some professional speakers are designed to put a high horn in front of its woofer, but for the low frequency emitted by this woofer, it simply can't see what is blocking the sound in front, so low frequency It can be passed on as usual. From our auditory point of view, we need to hear high-frequency sounds to distinguish different types of sounds, but if we simply talk about people's conversations, we only need to hear the frequency of 4kHz and below, we can immediately identify What is the person talking. For example, the voice transmission of the phone, the high frequency only reaches 4 kHz, so sometimes when a person who has not talked to you for a long time, when he calls you, just say "Hey!", you can immediately identify him. You haven’t heard the voice of a friend for a long time. We listen to high frequencies and have directionality, that is, we can identify the direction of high frequency sound sources. Because the high-frequency sound has passed to our two ears, there is already a very small time difference, so when they come to the ear, there are different phase changes. Can we identify this by changing the phase?
(1) Acoustic history When a tree in the forest collapses, a loud sound is heard, but no one is in this virgin forest, so this sound is not heard. Is this a sound coming out? The sound is definitely coming out, because when the trunk and branches touch the ground, they all produce some sound, but no one hears it, but the sound is heard by humans or other animals. It is different, so this is the psychology (Psychoacoustics).
The acoustic principle I am talking about here is mainly to let a tuner understand all aspects of acoustics, not acoustic research, or acoustics of master's and doctoral degrees, so the acoustic theory I have covered in this book is It can actually be used by people who operate the sound on site.
In 1915, an American named E. S. Pidham put a telephony listener on the horn of a record disc, and the sound was given to a group of people celebrating Christmas in San Francisco. Electroacoustics was born. After the end of the First World War, at the inauguration of President Harding in the United States, Bell Company connected the phone's dynamic listening device to the horn of the record player at that time, and was able to pass the voice to the president. A large group of people at the ceremony, so many professional audio research and the development of sound reinforcement engineering. Sound researchers are not only trying to improve audio equipment, but also doing various experiments to understand human response to hearing. But the most advanced audio research people understand that sound science is a holistic study. To understand every aspect of audio equipment and human physiological response to hearing, they have made great contributions in the past years and now. As early as 1877, Sir Raleigh of the United Kingdom had already done acoustic research. He once said: "All problems, whether directly or indirectly related to sound, must be decided with our ears because it It is our organ of hearing, and the decision of the ear should be the final decision. It is no longer necessary to accept the appeal. But this does not mean that all audio research is done by the ear alone. When we find that the foundation of the sound is a When we detect the phenomenon of physics, we must turn to another area of ​​physics. It is physics. The important rate can be studied from this aspect, and our hearing sense must accept these rates." It can be seen from the above paragraph that even in the absence of electroacoustic sound generation, older scientists believe that this is the realm of physics.
The famous scientist, Lord Calvin of the United Kingdom, often said: "When you measure what you say and can express it with numbers, you have some knowledge of it. But if you can't express it with numbers, then your Knowledge is still rudimentary and imperfect; for anything, this may be the source of knowledge, but your mind has not yet reached the realm of science.†Lord Calvin (1824—1907) was the best of the 19th century. One of the scientists, in order to commemorate the great man, the absolute temperature - 273.16 degrees Celsius is named 0 degrees Calvin.
Don & Carolyn Davis is the author of the book Sound System Engineering. Known as the Acoustic Bible, this book is almost a must-read for every foreign research sound. I quote this passage in his book: "The knowledge of mathematics and physics is a necessary condition for understanding sound engineering in essence. The deeper the understanding of these two kinds of science, the more you can cross the feelings that you get from feelings, The use of science to cite the facts. The famous audiophile James Moore once said: 'In sound science, anything that seems obvious on the surface is usually wrong.'
I quoted the instructions of several scientists and audiologists above, mainly because most of the people who do audio today are of course interested in sound and music, but think that they can identify what is right by their hearing. Good or bad sound, I don't understand that this is a professional engineering knowledge, it is not good sound. Sir Lai Li, who was far away from the 19th century, has pointed out that this is a scientific realm. Modern sound engineering is also working hard like other scientific academics, so acoustic engineering is inseparable from mathematics and physics.
(2) The live sound and the sound of the studio are separately operated in the live sound here. It has many different places from the recording technology. Many people think that the highest level of sound is the recording technology. This is not comprehensive. of. In the recording technology, basically there is no feedback, because when operating in a recording studio, all the peripheral factors can be controlled, but in the live audio replay, we can not avoid many live audio problems. So live audio and recording audio are two different kinds of learning. The requirements for live audio and studio audio are different, so there are many different devices. For example, in the mixing console used in the recording studio, each input has a plurality of parameter equalization, so that the sound engineer can finely adjust the input source of each input as much as possible to achieve the best sound source effect. A mixer for live audio, usually in each of its inputs, the balance is relatively simple. Because many times, the live tuner does not have a lot of time to fine-tune the sound source of each channel. In addition, the volume control fader of each channel in the live sound mixer can not only attenuate the volume, but also Can gain 10-14 dB. If you are working on a mixing studio for the studio, this putter does not need to be used for a lot of time, so the English name of this putter is fader, which means the attenuator. For high-power amplifiers used in live audio, they all have fans for cooling purposes, because live audio amplifiers often work at maximum power output, and there are many times when you are doing live sound outdoors, the surrounding temperature may be quite high. If you are in the studio, there will usually be air conditioning, the temperature will of course not be too high, and the amplifier in the recording studio is mainly used to push the monitor speakers. Of course, there is no need to output a large amount of power, so the amplifier only needs to use ordinary The heat sink can dissipate very little heat. If the amplifier is equipped with a fan, the sound from the fan will cause noise, so the amplifier in the recording room basically does not need a fan.
The speakers used in live audio, in order to spread a large sound pressure to the audience at a long distance, so they need to be very efficient, but the monitor speakers used in the recording studio are used by the sound engineer to monitor the sound source or The final result of the recording, the sound engineer is sitting close to the monitor speakers to monitor, so the monitor is a near-field speaker, does not require high sensitivity, the effect is completely different from the live audio speakers.
(3) The relationship between audio and wavelength Many live tuners do not care about the relationship between audio and wavelength. In fact, this is very important: audio and wavelength have a direct relationship with the speed of sound. At an altitude of air pressure, at a temperature of 21 degrees Celsius, the sound speed is 344m / s, and I contact domestic tuner, their usual sound speed is 34Om / s, this is the speed of the sound at 15 degrees Celsius, but The main thing to remember is that the speed of the sound changes with the air temperature and air pressure. The lower the temperature, the higher the molecular density in the air, so the speed of the sound will decrease, and if it is done at a high altitude. Sound, because the air pressure is reduced, the molecules in the air become scarce, and the sound speed increases. The relationship between audio and wavelength and sound is: wavelength = sound speed / frequency; λ = v / f, if the sound speed is assumed to be 344 m / s, the wavelength of 100Hz audio is 3.44 m, the wavelength of 1000hz (ie lkHz) It is 34.4 cm, and a 20 kHz audio wavelength is 1.7 cm.
(4) High, medium and low frequency of the speaker. For example, we now have an 18-hour cone speaker unit, which is installed in a wood-made speaker. The panel area of ​​this speaker is 1 square meter, which is the height of the panel. And the width is l meters. How do we calculate the high, medium and low frequencies of this speaker? First we have to calculate the diagonal length of the speaker panel, which is the square root of 2 = 1.414m, and the l/4 wavelength of any frequency is more than 1.414m. For this speaker it is low frequency; if the l/4 wavelength of a frequency is 1.414m, the wavelength is 4×1.414m= 5.656m, this frequency=344m/s÷5.656m=60.8/ s = 60.8 Hz, so any audio below 60.8 Hz is its low frequency for this speaker. When the frequency of 60.8 Hz or lower is transmitted from this speaker, their diffusion image is spherical, which is equal to the volume of these frequencies before and after the speaker and above and below when we hang the speaker in the middle of a room. The sound pressure emitted is almost the same, and the sound that is released becomes non-directional. When the l/4 wavelength of a certain frequency is smaller than the diagonal length of the speaker panel, but this wavelength is greater than the radius of the speaker, this frequency is the medium frequency of the speaker. For example, we now use an 18-hour unit with a radius of 9 inches, which is 22.86cm=0.2286m. This audio is 344m/s÷0.2286m=1505Hz. The frequency from 60.8Hz to 1505HZ is the medium frequency of this speaker. . The shape in which the medium frequency is diffused from the speaker is hemispherical. That is, if we release this frequency from the speaker that was hung in the center of the room, the shape of the sound diffusing from the speaker panel is hemispherical. Behind the speaker is the sound that does not hear this frequency. The frequency of 1505Hz and higher is its high frequency for this speaker. The shape of the sound that is diffused from the speaker at a high frequency is tapered, and the higher the frequency, the narrower the shape of the cone. Usually, if the frequency exceeds 4 times of the start of high audio, the shape of the sound will slowly become a straight line without spreading. If it is not sitting in the position of the alignment unit, these high frequencies will not be heard. Therefore, if many high-frequency units are paper cone type, the diameter of the paper cone is very small, and the high-frequency lower limit of the speaker is increased as much as possible, and it is desirable to increase the width of the high-frequency diffusion. We often see tweeters in home audio speakers, usually with a 1-2 cell or a hemispherical unit, for this reason. The tweeter of the professional live sound, because it has to emit a large high-frequency sound pressure, it must be treated with a horn.
(5) Different kinds of sound fields When a cone speaker receives the signal from the power amplifier, the paper cone will shake forward and backward. When the paper cone advances, the paper cone hits the air molecules in front of it. The air in front of the cone increases the pressure, and the molecules continue to push forward, colliding with the air molecules in front of them, causing a slight high pressure. When the cone is retreating, the air molecules in front of the cone create a slight vacuum, and then the molecules follow the cone back, causing a slight pressure drop in the air. But let's not forget that the air is elastic, but the air in front of the cone is just shaken by the action of the cone, and it cannot reach the elasticity of the air itself. At this time we have to look at the wavelength of this frequency, the sound is to leave until When the distance of the paper cone is 2.5 times the wavelength, the air exerts the elasticity of the sound. For example, a 100Hz frequency, its wavelength is 3.44 meters, so the sound is about 2.5 × 3.44 meters = 8.6 meters away from the paper cone, is the true 100Hz sound. If 10OHz is used, the distance from the paper cone is less than 8.6 meters, which is the near sound field of lOOHz, and more than 8.6 meters is the far sound field of 100Hz. Why do we need to understand the far and near sound field? Many times the electric bass player in a band, he often does not understand the effect of the near sound field, and on his electric bass speaker, there is an equalization knob is written Bass is the title of this musician. The electric bass player usually stands in a place not far from the electric bass speaker. If he stands in the near sound field, sometimes he feels that the bass is not enough, he will adjust the Bass equalization knob as much as possible, but the audience is Their position will hear very strong bass, and often cause bad results. These strong basses will also run into the singer's microphone. If the tuner feels that the singer's voice is not enough, he will improve the singer's voice, but at the same time, the electric bass will also increase the volume. The sound has encountered difficulties. The lowest E string of the electric bass is 41Hz, but because the pickup is placed at the end of the string, the first harmonic of the 41hz 82Hz is the main electric bass low frequency, and the 82Hz wavelength is 4.2m (344m/s). Divided by 82/s = 4.195m), so about 10 meters away from the electric bass speaker is the 82Hz far sound field, and because the electric bass player does not stand so far away from his speaker, The sound he heard was only the near sound field, not the sound heard by the audience. So when we talk about the far and near sound field of the speaker, the most important thing is to notice the frequency and its wavelength, instead of simply looking at how far away from the speaker is equal to the far or near sound field, the most important thing is to remember when we listen to music, To be in the far field, not in the near sound field.
(6) Direct sound field, reflected sound field, and non-direct sound field. When the speaker makes a sound in a room, the listener can hear the sound directly from the speaker. This is the direct sound field (indirectfield), but it can also be heard. The sound reflected from walls, ceilings and floors is called the reverberant field. The more the direct sound field is heard by the audience, the smaller the sound of the reflected sound field is, the better the sound is, because the sound of the direct sound field is controllable, but the sound of the reflected sound field is uncontrollable, only The sound from the direct breeding field will be dyed to reduce the clarity of the original sound, so the listener who is closer to the speaker will feel a better sound, and the audience sitting behind is likely It is the reflected sound field sound that they hear is louder than the direct sound field sound, the sound effect will be worse and the clarity will be reduced. Sometimes when a band plays on the stage, because they don’t have a monitor, and the main speakers on both sides are placed close to the mouth, the sounds heard by the band and the singer are not completely from the direct sound field. The position of standing is called the direct sound field, and the sound effect is certainly not good. This will also affect the performance level of the band, and the audience will not hear the sound of the performance.
(7) Interface Interference When we choose to place the speaker, it is important to note that the sound from the speaker is affected by the interface next to it. For example, the main speakers placed on both sides of the table, their bass cones off the ground and the wall next to it, if it is about 1 meter, a 4 meter wavelength audio will be interfered by these two interfaces. A frequency of 4 meters is 86Hz (344m / s ÷ 4m = 86Hz), when the sound of 86HZ is released from the speaker, the large air pressure just hits the ground and the wall within 1/4 weeks, and then l/4周就å射回到音箱的纸盆é¢å‰ï¼Œä½†è¿™ä¸ªæ—¶å€™åˆšå·§çº¸ç›†è¦åŽé€€ï¼ŒåŽŸæ¥ä»Žåœ°é¢åŠå¢™å£å射过æ¥çš„大空气压力就会被纸盆åŽé€€çš„åŠ¨ä½œæŠµæ¶ˆå¾ˆå¤šï¼Œé€ æˆå¤±åŽ»äº†å¾ˆé‡è¦çš„低音。如果é‡åˆ°è¿™ä¸ªæƒ…况，就应该把音箱å‘å°åŽé€€0．5ï¼1米，让音箱所å‘出æ¥çš„声音ä¸èƒ½ç›´æŽ¥å°„到地é¢ä¸Šï¼Œè€Œå¦‚æžœå¯ä»¥æŠŠéŸ³ç®±ç§»åˆ°é 近两边的墙å£æ—¶ï¼Œæ›´å¯åˆ©ç”¨å¢™å£çš„å射制åšå‡ºæ›´å¤§çš„音é‡ã€‚ 80-100Hz 这段频率是很é‡è¦çš„ï¼Œå®ƒæ˜¯æˆ‘ä»¬è‚ºéƒ¨ç©ºé—´çš„å…±é¸£ç‚¹ï¼Œä¹Ÿæ˜¯ä½ŽéŸ³é¼“çš„å…±é¸£é¢‘çŽ‡ï¼Œå¦‚æžœæ˜¯å› ä¸ºä¸äº†è§£ç•Œé¢å¹²æ‰°è€Œæ‘†é”™äº†éŸ³ç®±æ”¾ç½®çš„ä½ç½®ï¼Œå®žåœ¨æ˜¯å¾ˆä¸å€¼å¾—的。
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ç€å科å¦å®¶è‹±å›½çš„å¡å°”æ–‡å‹‹çˆµå¸¸å¸¸è¯´ï¼šâ€œå½“ä½ åº¦é‡ä½ 所述的事物，而能用数å—æ¥è¡¨è¾¾å®ƒï¼Œä½ å¯¹è¿™äº‹ç‰©å·²æœ‰äº›çŸ¥è¯†ã€‚ä½†å¦‚æžœä½ ä¸èƒ½ç”¨æ•°å—æ¥è¡¨è¾¾å®ƒï¼Œé‚£ä¹ˆä½ 的知识ä»ç„¶æ˜¯ç®€é™‹çš„å’Œä¸å®Œæ»¡çš„；对任何事物而言，这å¯èƒ½æ˜¯çŸ¥è¯†çš„始æºï¼Œä½†ä½ çš„æ„念还未达到科å¦çš„境界。â€å¡å°”文勋爵(1824—1907)是19世纪最出色的科å¦å®¶ä¹‹ä¸€ï¼ŒåŽä¸–的科å¦å®¶ä¸ºäº†è¦çºªå¿µè¿™ä½ä¼Ÿäººï¼ŒæŠŠç»å¯¹æ¸©åº¦â€”273．16æ‘„æ°åº¦å‘½å为0度å¡å°”文度。
戴维斯夫妇(Don＆ Carolyn Davis)是《音å“系统工程》(Sound System Engineering)这本书的作者。这书被称为音å“圣ç»ï¼Œå‡ 乎是æ¯ä¸€ä¸ªå¤–å›½ç ”ç©¶éŸ³å“的人必读之物。我引述他书内这一段：“具有数å¦å’Œç‰©ç†å¦çš„知识，是实质上了解音å“工程å¦çš„å¿…è¦æ¡ä»¶ã€‚对这两ç§ç§‘å¦è®¤è¯†è¶Šæ·±ï¼Œè¶Šèƒ½ä½¿ä½ 跨越从感觉上所得到的æ„念，而达到用科å¦æ¥å¼•è¯äº‹å®žã€‚ç€å音å“家å 士摩亚曾ç»è¯´è¿‡ï¼š'在音å“å¦ä¸ï¼Œä»»ä½•åœ¨è¡¨é¢çœ‹æ¥å¾ˆæ˜Žæ˜¾çš„事情，通常都是错误的'。â€
æˆ‘åœ¨ä»¥ä¸Šå¼•è¿°äº†å‡ ä½ç§‘å¦å®¶åŠéŸ³å“å¦å®¶çš„è®è¨€ï¼Œä¸»è¦æ˜¯å› 为现在大部分åšéŸ³å“的人士，他们当然是对音å“åŠéŸ³ä¹å¾ˆæœ‰å…´è¶£ï¼Œä½†æ˜¯ä»¥ä¸ºå…‰é 他们的å¬è§‰å°±å¯ä»¥é‰´å®šä»€ä¹ˆæ˜¯å¥½æˆ–ä¸å¥½çš„音å“，ä¸æ˜Žç™½è¿™æ˜¯ä¸€é—¨ä¸“业的工程å¦é—®ï¼Œæ˜¯åšä¸å¥½éŸ³å“的。远在19世纪的莱æŽçˆµå£«å·²ç»æŒ‡å‡ºè¿™æ˜¯ä¸€ä¸ªç§‘å¦çš„境界，现代的音å“工程å¦ä¹Ÿåƒå…¶å®ƒç§‘å¦å¦æœ¯ä¸€æ ·æ£åœ¨åŠªåŠ›åœ°å‘展，所以音å“工程å¦æ˜¯ç¦»ä¸å¼€æ•°å¦åŠç‰©ç†å¦çš„。
(2)现场音晌与录音室音晌的分别在这里所讲解的现场音å“地æ“作，它与录音技术是有很多ä¸åŒçš„地方，有很多人以为音å“的最高境界就是录音技术，这是ä¸å…¨é¢çš„。在录音技术上，基本是没有碰到åé¦ˆçš„æƒ…å†µï¼Œå› ä¸ºåœ¨ä¸€ä¸ªå½•éŸ³å®¤å†…è¿›è¡Œæ“ä½œæ—¶ï¼Œæ‰€æœ‰çš„å¤–å›´å› æ•°éƒ½å¯ä»¥å¾—到控制，但是在现场音å“é‡æ’时，我们是ä¸å¯ä»¥é¿å…有很多现场音å“的问题，所以现场音å“和录音音å“是两ç§ä¸åŒçš„å¦é—®ã€‚现场音å“跟录音室音å“çš„è¦æ±‚是ä¸åŒçš„，所以有很多器æ也是ä¸åŒçš„。例如在录音室内所用的调音å°ï¼Œå®ƒä»¬çš„æ¯è·¯è¾“入都有多个å‚æ•°å‡è¡¡ï¼Œè®©å½•éŸ³å¸ˆå¯ä»¥æŠŠæ¯è·¯è¾“入的音æºå°½é‡åšæœ€ç²¾å¯†åœ°å¾®è°ƒï¼ŒåŠ¡æ±‚达到最好的音æºæ•ˆæžœã€‚ A mixer for live audio, usually in each of its inputs, the balance is relatively simple.å› ä¸ºå¾ˆå¤šæ—¶å€™ï¼ŒçŽ°åœºè°ƒéŸ³å¸ˆæ ¹æœ¬å°±æ²¡æœ‰å¾ˆå¤šæ—¶é—´æŠŠæ¯è·¯çš„音æºåšå¾ˆä»”细地微调，而在现场音å“的调音å°æ¯è·¯çš„音é‡æŽ§åˆ¶æŽ¨æ†ï¼Œå®ƒä»¬é™¤äº†å¯ä»¥æŠŠéŸ³é‡åšè¡°å‡å¤–，也å¯ä»¥å¢žç›Š10—14 dB。 If you are working on a mixing studio for the studio, this putter does not need to be used for a lot of time, so the English name of this putter is fader, which means the attenuator. For high-power amplifiers used in live audio, they all have fans for cooling purposes, because live audio amplifiers often work at maximum power output, and there are many times when you are doing live sound outdoors, the surrounding temperature may be quite high. If you are in the studio, there will usually be air conditioning, the temperature will of course not be too high, and the amplifier in the recording studio is mainly used to push the monitor speakers. Of course, there is no need to output a large amount of power, so the amplifier only needs to use ordinary The heat sink can dissipate very little heat.如果功放装有风扇的è¯ï¼Œé£Žæ‰‡å‘出æ¥çš„声音åè€Œé€ æˆå™ªéŸ³ï¼Œæ‰€ä»¥åœ¨å½•éŸ³å®¤å†…的功放基本上是ä¸éœ€è¦é£Žæ‰‡çš„。
现场音å“所用的音箱，为ç€è¦æŠŠå¾ˆå¤§çš„å£°åŽ‹ä¼ æ’绘在远è·ç¦»çš„观众，所以它们是需è¦å¾ˆé«˜æ•ˆçŽ‡çš„，但在录音室内所用的监å¬éŸ³ç®±ï¼Œæ˜¯å½•éŸ³å¸ˆç”¨æ¥ç›‘å¬å£°æºæˆ–录音的最åŽç»“果，录音师是å在è·ç›‘å¬éŸ³ç®±å¾ˆè¿‘的地方æ¥ç›‘å¬ï¼Œæ‰€ä»¥ç›‘å¬éŸ³ç®±æ˜¯ä¸€ç§è¿‘音场的音箱，ä¸éœ€è¦é«˜çµæ•åº¦ï¼Œä½œç”¨è·ŸçŽ°åœºéŸ³å“音箱是完全ä¸åŒçš„。
(3)音频与波长的关系很多现场调音师都没有ç†ä¼šåˆ°éŸ³é¢‘与波长的关系，其实这是很é‡è¦çš„：音频åŠæ³¢é•¿ä¸Žå£°éŸ³çš„速度是有直接的关系。在海拔空气压力下，21æ‘„æ°æ¸©åº¦æ—¶ï¼Œå£°éŸ³é€Ÿåº¦ä¸º344mï¼s，而我接触国内的调音师，他们常用的声音速度是34Omï¼s，这个是在15æ‘„æ°åº¦çš„温度时声音的速度，但大家最主è¦è®°å¾—就是声音的速度会éšç€ç©ºæ°”温度åŠç©ºæ°”压力而改å˜çš„，温度越低，空气里的分å密度就会增高，所以声音的速度就会下é™ï¼Œè€Œå¦‚果在高海拔的地方åšçŽ°åœºéŸ³å“ï¼Œå› ä¸ºç©ºæ°”åŽ‹åŠ›å‡å°‘，空气内的分åå˜å¾—ç¨€å°‘ï¼Œå£°éŸ³é€Ÿåº¦å°±ä¼šå¢žåŠ ã€‚éŸ³é¢‘åŠæ³¢é•¿ä¸Žå£°éŸ³çš„关系是：波长=声音速度ï¼é¢‘率； λ=vï¼f，如果å‡å®šéŸ³é€Ÿæ˜¯344 mï¼s时，100Hz的音频的波长就是3．44 m，1000hz(å³lkHz)的波长就是34．4 cm，而一个20kHz的音频波长为1．7cm。
(4)音箱的高ã€ä¸ã€ä½Žé¢‘率例如我们现在有一个18时的纸盆扬声器å•å…ƒï¼Œè£…置在一个用木æé€ çš„éŸ³ç®±å†…ï¼Œè€Œè¿™éŸ³ç®±çš„é¢æ¿é¢ç§¯æ˜¯l平方米，å³è¿™é¢æ¿çš„高度åŠå®½åº¦å‡æ˜¯lç±³ã€‚æˆ‘ä»¬æ€Žæ ·è®¡ç®—è¿™éŸ³ç®±çš„é«˜ã€ä¸ã€ä½Žé¢‘率呢?首先我们è¦è®¡ç®—这音箱é¢æ¿çš„对角长度，是2çš„æ–¹æ ¹=1．414m，任何频率的lï¼4波长是超过1．414m时，对这音箱æ¥è¯´å®ƒå°±æ˜¯ä½Žé¢‘；如果一个频率的lï¼4波长是1．414m时，波长就是4×1．414m= 5．656m，这频率=344mï¼s÷5．656m=60．8ï¼s=60．8Hz，所以任何音频低于60．8Hz时，对这音箱æ¥è¯´å°±æ˜¯å®ƒçš„低频率。当60．8Hzæˆ–æ›´ä½Žçš„é¢‘çŽ‡ä»Žè¿™éŸ³ç®±ä¼ æ’出æ¥æ—¶ï¼Œå®ƒä»¬çš„扩散形象是çƒåž‹çš„，ç‰äºŽå¦‚果我们把这音箱悬挂在一个房间ä¸é—´æ—¶ï¼Œè¿™äº›é¢‘率的音é‡åœ¨éŸ³ç®±çš„å‰åŽå·¦å³åŠä¸Šä¸‹æ‰€å‘出æ¥çš„声压都是差ä¸å¤šçš„，放出æ¥çš„声音å˜æˆæ²¡æœ‰æ–¹å‘性。当æŸé¢‘率的lï¼4波长是å°äºŽéŸ³ç®±é¢æ¿çš„对角长度，但这波长åˆå¤§äºŽæ‰¬å£°å™¨çš„åŠå¾„时，这段频率就是这音箱的ä¸é¢‘率。例如我们现在是用一个18æ—¶å•å…ƒï¼Œè¿™å•å…ƒçš„åŠå¾„为9寸，就是22.86cm=0.2286m,这个音频为344m/s÷0．2286m=1505Hz,从60.8Hz-1505HZ频就是这音箱的ä¸é¢‘率。ä¸é¢‘率从这音箱所扩散出æ¥çš„形状是åŠçƒå½¢çš„，å³å¦‚果我们把这段频率从刚æ‰æ‚¬æŒ‚在房间ä¸å¿ƒçš„音箱放出æ¥æ—¶ï¼Œå£°éŸ³ä»ŽéŸ³ç®±é¢æ¿æ‰©æ•£å‡ºæ¥çš„形状是åŠçƒå½¢ã€‚在音箱åŽé¢æ˜¯å¬ä¸åˆ°è¿™æ®µé¢‘率的声音。1505HzåŠæ›´é«˜çš„频率，对这音箱æ¥è¯´å°±æ˜¯å®ƒçš„高频率。高频率从音箱扩散出æ¥çš„声音形状是锥形的，频率越高，锥的形状越窄。通常如果频率超过开始高音频的4å€æ—¶ï¼Œå£°éŸ³æ‰©æ•£å‡ºæ¥çš„形状会慢慢å˜æˆä¸€æ¡ç›´çº¿è€Œä¸æ‰©æ•£ï¼Œå¦‚æžœä¸æ˜¯å在对æ£å•å…ƒçš„ä½ç½®ï¼Œå°±å¬ä¸åˆ°è¿™äº›é«˜é¢‘率。所以很多高频率å•å…ƒå¦‚果是纸盆型的è¯ï¼Œè¿™çº¸ç›†çš„直径是很å°çš„，把这音箱的高频下é™å°½é‡æé«˜ï¼Œå¸Œæœ›èƒ½å¤Ÿä½¿é«˜é¢‘æ‰©æ•£çš„å®½åº¦å¢žåŠ ã€‚æˆ‘ä»¬å¸¸å¸¸è§åˆ°å®¶åºéŸ³å“音箱ä¸çš„高音å•å…ƒï¼Œé€šå¸¸ä¼šç”¨l—2时的纸盆å•å…ƒï¼Œæˆ–åŠçƒçŠ¶çš„å•å…ƒï¼Œç†ç”±å°±æ˜¯è¿™ä¸ªåŽŸå› 。而专业现场音å“的高音å•å…ƒï¼Œå› 为è¦å‘出很大的高频声压，所以说一定是采用å·è§’处ç†çš„。
(5)å„ç±»ä¸åŒçš„音场当一个纸盆扬声器接å—äº†ä»ŽåŠŸæ”¾ä¼ è¿‡æ¥çš„ä¿¡å·åŽï¼Œçº¸ç›†å°±ä¼šä½œå‡ºå‰åŽçš„摇动，当纸盆å‘å‰æŽ¨è¿›æ—¶ï¼Œçº¸ç›†æ’žå‡»åˆ°å®ƒå‰é¢çš„空气分å，在纸盆å‰é¢çš„ç©ºæ°”å°±ä¼šå¢žåŠ åŽ‹åŠ›ï¼Œè¿™äº›åˆ†å就会继ç»å‘å‰æŽ¨è¿›ï¼Œç¢°æ’žå®ƒä»¬å‰é¢çš„空气分åï¼Œé€ æˆè½»å¾®çš„高气压。当纸盆å‘åŽé€€æ—¶ï¼Œçº¸ç›†å‰é¢çš„空气分å就会产生轻微的真空，然åŽè¿™äº›åˆ†å会跟ç€çº¸ç›†çš„åŽé€€ï¼Œé€ æˆè¿™é‡Œçš„空气有轻微的压力å‡å°‘。但我们ä¸è¦å¿˜è®°ï¼Œç©ºæ°”是有弹力的，但在纸盆å‰é¢çš„空气是刚刚被纸盆的动作摇动，ä¸èƒ½è¾¾åˆ°ç©ºæ°”本身的弹力，这时我们便è¦çœ‹è¿™é¢‘率的波长，声音是è¦ç›´åˆ°ç¦»å¼€çº¸ç›†çš„è·ç¦»æœ‰2．5å€æ³¢é•¿æ—¶ï¼Œè¿™äº›ç©ºæ°”æ‰å‘æŒ¥å‡ºé€ æˆå£°éŸ³çš„弹力。例如一个100Hz的频率，它的波长是3．44米，所以声音è¦ç¦»å¼€çº¸ç›†2．5×3．44ç±³=8．6米之外，æ‰æ˜¯çœŸæ£çš„这个100Hz的声音。如果用10OHzæ¥ç®—，离开纸盆的è·ç¦»è¿˜æ²¡è¾¾åˆ°8．6米就为lOOHz的近音场，而超过8．6ç±³æ‰æ˜¯100Hz的远音场。为什么我们è¦äº†è§£è¿œè¿‘音场呢?很多时候在一队ä¹é˜Ÿä¸çš„电è´å¸æ‰‹ï¼Œä»–往往都ä¸äº†è§£è¿‘音场的效果，而在他的电è´å¸éŸ³ç®±ä¸Šï¼Œæœ‰ä¸€ä¸ªå‡è¡¡æ—‹é’®å°±æ˜¯å†™ç€è´å¸ï¼ˆBass) ，æ£æ˜¯è¿™ä¹æ‰‹çš„称å·ã€‚电è´å¸æ‰‹é€šå¸¸ä¼šç«™åœ¨ç¦»å¼€ç”µè´å¸éŸ³ç®±ä¸è¿œçš„地方åšæ¼”å¥ï¼Œå¦‚果他站在近音场时，有时会觉得低音ä¸è¶³ï¼Œå°±ä¼šæŠŠè¿™Bassçš„å‡è¡¡æ—‹é’®å°½é‡è°ƒå¤§ï¼Œä½†å¬ä¼—在他们的ä½ç½®å°±ä¼šå¬å¾—åˆ°å¾ˆå¼ºçƒˆçš„ä½ŽéŸ³ï¼Œå¾ˆå¤šæ—¶å€™é€ æˆä¸å¥½çš„效果。这些强烈的低音也会跑进æŒæ‰‹çš„è¯ç’ï¼Œå¦‚æžœè°ƒéŸ³å¸ˆå› ä¸ºè§‰å¾—æŒæ‰‹çš„声音ä¸è¶³å¤Ÿæ—¶ï¼Œå°±ä¼šæŠŠæŒæ‰‹è¿™ä¸€è·¯çš„声音æ高，但也åŒæ—¶æŠŠç”µè´å¸çš„低音é‡ä¹Ÿæ高了，调音就é‡ä¸Šäº†å›°éš¾ã€‚电è´å¸çš„最低E弦是41Hzï¼Œä½†å› ä¸ºæ‹¾éŸ³å™¨æ˜¯æ”¾åœ¨å¼¦çš„æœ«æ®µï¼Œæ‰€ä»¥41hz第一个è°éŸ³82Hzæ‰æ˜¯ä¸»è¦çš„电è´å¸ä½Žé¢‘率，82Hz的波长是4．2米（344mï¼s 除以82ï¼s=4.195m），所以差ä¸å¤šè¦ç¦»å¼€ç”µè´å¸éŸ³ç®±10米左å³æ‰æ˜¯è¿™82Hzçš„è¿œéŸ³åœºï¼Œè€Œå› ä¸ºç”µè´å¸æ‰‹ä¸ä¼šç«™åˆ°ç¦»å¼€ä»–的音箱这么远的è·ç¦»æ—¶ï¼Œä»–å¬åˆ°çš„声音åªæ˜¯è¿‘音场，而ä¸æ˜¯å¬ä¼—所å¬å¾—到的声音。所以我们当说到扬声器的远近音场时，最主è¦æ˜¯æ³¨æ„到频率åŠå®ƒçš„波长，而ä¸æ˜¯å•çº¯çœ‹ç¦»å¼€éŸ³ç®±å¤šè¿œå°±æ˜¯ç‰äºŽè¿œæˆ–近音场，最主è¦å°±æ˜¯è®°å¾—我们当欣èµéŸ³ä¹æ—¶ï¼Œæ˜¯è¦åœ¨è¿œéŸ³åœºçš„ä½ç½®ï¼Œè€Œä¸æ˜¯åœ¨è¿‘音场的ä½ç½®ã€‚
（6）直接音场ã€å射音场ã€ä¸ç›´æŽ¥éŸ³åœºå½“扬声器在一个房间内å‘出声音，å¬ä¼—å¯ä»¥å¬åˆ°ç›´æŽ¥ä»Žæ‰¬å£°å™¨ä¼ 过æ¥çš„声音，这就是直接音场（indirectfield），但也å¯ä»¥å¬åˆ°ä»Žå¢™ã€å¤©èŠ±æ¿åŠåœ°æ¿æ‰€å射过æ¥çš„声音，这就å«åšå射音场（reverberant field)。å¬ä¼—å¬åˆ°è¶Šå¤šçš„直接音场的声音，å射音场的声音就越å°æ—¶ï¼Œè¿™å£°éŸ³å°±è¶Šå¥½ï¼Œå› 为直接音场的声音是å¯ä»¥æŽ§åˆ¶çš„，但å射音场的声音是ä¸èƒ½æŽ§åˆ¶çš„，åªä¼šæŠŠç›´æŽ¥è‚²åœºå‘出æ¥çš„å£°éŸ³åŠ ä¸Šå–§æŸ“ï¼ŒæŠŠåŽŸæœ¬å£°éŸ³çš„æ¸…æ™°åº¦åº•å‡ä½Žï¼Œæ‰€ä»¥å得离音箱比较近的å¬ä¼—就会感觉到好一点的音å“效果，而å在åŽé¢çš„å¬ä¼—很å¯èƒ½æ˜¯ä»–们å¬åˆ°çš„å射音场声音比直接音场声音更大，音å“效果便会比较差åŠæ¸…晰度é™ä½Žã€‚有时候一队ä¹é˜Ÿåœ¨å°ä¸Šæ¼”å‡ºæ—¶ï¼Œå› ä¸ºä»–ä»¬æ²¡æœ‰ç›‘å¬éŸ³ç®±ï¼Œè€Œä¸¤æ—的主音箱是放在é è¿‘å°å£çš„ä½ç½®ï¼Œä¹é˜ŸåŠæŒæ‰‹æ‰€å¬åˆ°çš„声音完全没有从直接音场放过æ¥çš„，他们站立的ä½ç½®å°±å«åšä¸ç›´æŽ¥éŸ³åœºï¼Œå£°éŸ³æ•ˆæžœå½“然ä¸ä¼šå¥½ï¼Œè¿™ä¹Ÿä¼šå½±å“到ä¹é˜Ÿçš„表演水平，令观众å¬åˆ°ä¸å¤ªå¥½çš„演出声音。
（7）界é¢å¹²æ‰°å½“我们选择放置音箱的ä½ç½®æ—¶ï¼Œå¾ˆé‡è¦çš„一环是è¦æ³¨æ„到音箱所å‘出æ¥çš„声音是会å—到它æ—边的界é¢å½±å“è€Œé€ æˆå¹²æ‰°ã€‚例如放在å°å£ä¸¤æ—的主音箱，它们的低音纸盆离开地é¢åŠæ—边的墙å£å¦‚果是大约在1米的时候，一个4米波长的音频就会å—到这两个界é¢çš„干扰。一个4米波长的频率是86Hz（344mï¼s ÷ 4mï¼ 86Hz），当86HZ的声音从音箱放出æ¥æ—¶ï¼Œå¤§çš„空气压力在1ï¼4周内刚巧碰到地é¢åŠå¢™å£ï¼Œå†è¿‡lï¼4周就å射回到音箱的纸盆é¢å‰ï¼Œä½†è¿™ä¸ªæ—¶å€™åˆšå·§çº¸ç›†è¦åŽé€€ï¼ŒåŽŸæ¥ä»Žåœ°é¢åŠå¢™å£å射过æ¥çš„大空气压力就会被纸盆åŽé€€çš„åŠ¨ä½œæŠµæ¶ˆå¾ˆå¤šï¼Œé€ æˆå¤±åŽ»äº†å¾ˆé‡è¦çš„低音。如果é‡åˆ°è¿™ä¸ªæƒ…况，就应该把音箱å‘å°åŽé€€0．5ï¼1米，让音箱所å‘出æ¥çš„声音ä¸èƒ½ç›´æŽ¥å°„到地é¢ä¸Šï¼Œè€Œå¦‚æžœå¯ä»¥æŠŠéŸ³ç®±ç§»åˆ°é 近两边的墙å£æ—¶ï¼Œæ›´å¯åˆ©ç”¨å¢™å£çš„å射制åšå‡ºæ›´å¤§çš„音é‡ã€‚80-100Hz 这段频率是很é‡è¦çš„ï¼Œå®ƒæ˜¯æˆ‘ä»¬è‚ºéƒ¨ç©ºé—´çš„å…±é¸£ç‚¹ï¼Œä¹Ÿæ˜¯ä½ŽéŸ³é¼“çš„å…±é¸£é¢‘çŽ‡ï¼Œå¦‚æžœæ˜¯å› ä¸ºä¸äº†è§£ç•Œé¢å¹²æ‰°è€Œæ‘†é”™äº†éŸ³ç®±æ”¾ç½®çš„ä½ç½®ï¼Œå®žåœ¨æ˜¯å¾ˆä¸å€¼å¾—的。
（8）高ã€ä½ŽéŸ³æ•ˆæžœæˆ‘们很难指定æŸä¸€é¢‘率以上为高音或æŸé¢‘率以下为低音，我们常常说人的å¬è§‰æ˜¯ä»Ž20Hhï¼20KHz，但20kHz的频率是很少人能够å¬åˆ°çš„，通常åªæœ‰20å²ä»¥ä¸‹çš„é’年人，他们的耳朵没有å—到任何的æŸåæ—¶æ‰å¯ä»¥å¬å¾—到。如果åšå¬è§‰æµ‹éªŒï¼Œæœ€é«˜çš„测å¬é¢‘率åªæ˜¯8 kHzã€‚å½“å£°éŸ³ä¼ å‡ºåŽ»æ—¶ï¼Œé«˜é¢‘çŽ‡æ˜¯æ¯”ä½Žé¢‘çŽ‡è¡°å‡å¿«å¾—多，如果用1kHzè·Ÿ10kHzåšæ¯”较时，当声音跑了100ç±³åŽï¼Œ10kHzçš„'频率比起IkHz的音é‡ä¼šè¡°å‡30ï¼35dB的。（请å‚看图①）比起低频率，高频率声音是比较有方å‘性的。高频率的声音从å•å…ƒè·‘了出æ¥åŽï¼Œå¦‚æžœå—到物体的阻挡，高音就ä¸èƒ½å†ä¼ 过去，这个是跟低频率有很大的ä¸åŒï¼Œå› 为高频率的波长是比较çŸï¼Œå—到物体阻挡之åŽä¸ä¼šè½¬å¼¯ï¼Œä½†ä½Žé¢‘率的波长是比较长，所以很多时候就算有物体在å‰é¢é˜»æŒ¡ï¼Œä½Žé¢‘率也å¯ä»¥è½¬å¼¯è¿‡åŽ»ã€‚例如有些专业音箱的设计是把一个高音å·è§’放在它的低音å•å…ƒå‰é¢ï¼Œä½†å¯¹è¿™ä¸ªä½ŽéŸ³å•å…ƒæ‰€å‘出æ¥çš„ä½Žé¢‘çŽ‡ï¼Œå®ƒæ ¹æœ¬å°±çœ‹ä¸åˆ°å‰é¢æ˜¯æœ‰ä»€ä¹ˆä¸œè¥¿é˜»æŒ¡å£°éŸ³ä¼¼çš„，所以低频率å¯ä»¥ç…§æ ·ä¼ 过去。 从我们的å¬è§‰ä¸Šæ¥è¯´ï¼Œæˆ‘们是需è¦å¬åˆ°é«˜é¢‘率的声音æ¥è¾¨åˆ«å„ç±»ä¸åŒçš„声音，但如果å•çº¯æ˜¯è®²äººçš„è°ˆè¯å£°æ—¶ï¼Œæˆ‘们åªéœ€è¦å¬åˆ°4kHzåŠä»¥ä¸‹çš„频率，就能马上辨别是什么人在说è¯ã€‚例如电è¯çš„å£°éŸ³ä¼ é€ï¼Œé«˜é¢‘åªè¾¾åˆ°4kHzï¼Œæ‰€ä»¥æœ‰æ—¶å€™å½“ä¸€ä¸ªå¾ˆä¹…éƒ½æ²¡æœ‰å’Œä½ è°ˆè¯çš„人，当他打电è¯ç»™ä½ 时，åªè¦è¯´ï¼šâ€œå–‚ï¼â€ï¼Œä½ 就马上便å¯ä»¥é‰´åˆ«ä»–æ˜¯ä½ å¾ˆä¹…éƒ½æ²¡æœ‰è°ˆè¿‡è¯çš„朋å‹çš„声音。我们å¬é«˜é¢‘也有方å‘性，å³æ˜¯æˆ‘们能够辨别高频声音æ¥æºçš„æ–¹å‘ã€‚å› ä¸ºé«˜é¢‘çš„å£°éŸ³ä¼ åˆ°æˆ‘ä»¬ä¸¤ä¸ªè€³æœµæ—¶ï¼Œå·²ç»æœ‰äº†å¾ˆç»†å¾®çš„时间差，所以它们æ¥åˆ°è€³æœµçš„时候有ä¸åŒçš„相ä½æ”¹å˜ï¼Œæˆ‘们就借ç€è¿™æ”¹å˜äº†çš„相ä½å¯ä»¥é‰´å®š?
53 Jack.We are manufacturer of 6p6c Female Connector in China, if you want to buy RJ11 Jack Full Plastic MINI,6 Pin RJ11 Modular Connector,RJ11 Jack Full Shielded please contact us.
The RJ-45 interface can be used to connect the RJ-45 connector. It is suitable for the network constructed by twisted pair. This port is the most common port, which is generally provided by Ethernet hub. The number of hubs we usually talk about is the number of RJ-45 ports. The RJ-45 port of the hub can be directly connected to terminal devices such as computers and network printers, and can also be connected with other hub equipment and routers such as switches and hubs.
6p6c Female Connector,RJ11 Jack Full Plastic MINI,6 Pin RJ11 Modular Connector,RJ11 Jack Full Shielded
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