78 noise

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H. callahan
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Re: 78 noise

Post by H. callahan » 14 Aug 2019 04:51

Coffee Phil wrote:
13 Aug 2019 09:08
Of coarse I assume that acoustic records are pretty close to constant amplitude. It is a rational assumption when I observe that virtually all my acoustic records sound pretty good when played back constant amplitude and shrill when played back constant velocity.

Now maybe having your pants fall off at a disco is an explanation of why acoustic records must be constant velocity, but I don't quite follow it. Regardless of what the Village People or Donna Summer might say, I still say that every acoustic record which I have played appears to be close to CONSTANT AMPLITUDE.

Phil
If you would go into the example of the acoustic guitar, i´d be able to explain what i mean.

Anyway you got your opinion, so have a nice day!

Coffee Phil
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Re: 78 noise

Post by Coffee Phil » 14 Aug 2019 21:05

Hi H. callahan,

Is this what you are referring to?



One more example, which regretfully isn´t in the mathematical/physical language:

Let´s say there is an acoustic guitar and the lowest note it can play was 100Hz. You plug the string to make it vibrate at 100Hz and a certain amplitude and you need some ammount of mechanical energy to do so.
Now you press the string down in the middle to create a 200Hz frequency when being plugged. When oscillating at 200Hz the string does have to move double as much per second, at double the speed at least - so if you want it to oscillacte at same amplitude as at 100Hz you´ll have to bring up double the mechanical energy at least, maybe even four times as much.
To make it oscillate with same amplitude at 400Hz you´ll need four times the mechanical energy at least, at 800Hz its 8 times at least, at 1600Hz its 16 times, at 3200Hz its 32 times and at 6400Hz it was 64 times at least.

This would mean that playing a high note on an acoustic guitar would take the player 64 times the force at least to play this high note at same volume, if nature of soundwaves was constant amplitude - which it is not.

Playing a high note having the same volume on a guitar does not take 64 times the force, but about the same.
Therefore i conclude that nature of soundwaves is not constant amplitude but velocity.



I will agree that it is not in any mathematical/physical language which I know.

Phil



H. callahan wrote:
14 Aug 2019 04:51
Coffee Phil wrote:
13 Aug 2019 09:08
Of coarse I assume that acoustic records are pretty close to constant amplitude. It is a rational assumption when I observe that virtually all my acoustic records sound pretty good when played back constant amplitude and shrill when played back constant velocity.

Now maybe having your pants fall off at a disco is an explanation of why acoustic records must be constant velocity, but I don't quite follow it. Regardless of what the Village People or Donna Summer might say, I still say that every acoustic record which I have played appears to be close to CONSTANT AMPLITUDE.

Phil
If you would go into the example of the acoustic guitar, i´d be able to explain what i mean.

Anyway you got your opinion, so have a nice day!
Last edited by Coffee Phil on 14 Aug 2019 21:58, edited 2 times in total.

Bob Dillon
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Re: 78 noise

Post by Bob Dillon » 14 Aug 2019 21:42

Modern Gramophones and Electrical Reproducers (pub. 1929) - page 33

In discussing the recorder, claims are for :

Frequencies below 300 hz - constant amplitude
300 hz to 5000 hz - constant velocity
Beyond 5000 hz - constant acceleration

Table of contents : https://archive.org/details/ModernGramo ... reproducer The entire chapter 1 at least is worth a read
Jump to page 24 & 25 (in the book itself).

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Re: 78 noise

Post by Coffee Phil » 14 Aug 2019 23:13

Hi Bob,

Thanks for finding this book. It is defiantly not an easy read, not only because it is technical, but the language has changed in the near one century since it was published. With sufficient time and coffee one can gain understanding from it.
It appears that in 1929 network theory was better understood from an electrical standpoint (at least by telephone folks) than mechanical and they were developing mechanical analogs to the electrical filter theory which they had a better grasp of.

I will bookmark this and try to wade through it.

Phil

Bob Dillon wrote:
14 Aug 2019 21:42
Modern Gramophones and Electrical Reproducers (pub. 1929) - page 33

In discussing the recorder, claims are for :

Frequencies below 300 hz - constant amplitude
300 hz to 5000 hz - constant velocity
Beyond 5000 hz - constant acceleration

Table of contents : https://archive.org/details/ModernGramo ... reproducer The entire chapter 1 at least is worth a read
Jump to page 24 & 25 (in the book itself).

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Re: 78 noise

Post by Bob Dillon » 15 Aug 2019 00:37

Some of the book is a slog for sure.

H. callahan
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Re: 78 noise

Post by H. callahan » 15 Aug 2019 04:45

Coffee Phil wrote:
14 Aug 2019 21:05
Hi H. callahan,

Is this what you are referring to?



One more example, which regretfully isn´t in the mathematical/physical language:

Let´s say there is an acoustic guitar and the lowest note it can play was 100Hz. You plug the string to make it vibrate at 100Hz and a certain amplitude and you need some ammount of mechanical energy to do so.
Now you press the string down in the middle to create a 200Hz frequency when being plugged. When oscillating at 200Hz the string does have to move double as much per second, at double the speed at least - so if you want it to oscillacte at same amplitude as at 100Hz you´ll have to bring up double the mechanical energy at least, maybe even four times as much.
To make it oscillate with same amplitude at 400Hz you´ll need four times the mechanical energy at least, at 800Hz its 8 times at least, at 1600Hz its 16 times, at 3200Hz its 32 times and at 6400Hz it was 64 times at least.

This would mean that playing a high note on an acoustic guitar would take the player 64 times the force at least to play this high note at same volume, if nature of soundwaves was constant amplitude - which it is not.

Playing a high note having the same volume on a guitar does not take 64 times the force, but about the same.
Therefore i conclude that nature of soundwaves is not constant amplitude but velocity.



I will agree that it is not in any mathematical/physical language which I know.

Phil
Yes.
After this example of the acoustic guitar there was a question for you .

Coffee Phil
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Re: 78 noise

Post by Coffee Phil » 15 Aug 2019 18:45

Hi H. callahan,

Sorry, I guess I thought the question was rhetorical.

OK, there are several statements there.

First I believe you are saying that if you have guitar string which is tuned to 100 Hz, then shorten it to where it is tuned to 200 Hz. To achieve the same amplitude of vibration two times the energy will have to be stored in it at 200 Hz than required at 100 Hz. To that, I don't know the answer.

From the above you conclude that by nature sound waves are constant velocity as opposed to constant amplitude. I have no idea what might be meant by constant amplitude sound waves other that sounds of the same volume. The velocity of propagation of sound is ~ 1100 ft/second at sea level and I don't think that is a strong function of frequency, so I would say sound waves have constant velocity.

How any of the above relates to how a diaphragm in an acoustic cutting head responds to sound pressure of varying frequencies so far escapes me.

Phil




H. callahan wrote:
15 Aug 2019 04:45
Coffee Phil wrote:
14 Aug 2019 21:05
Hi H. callahan,

Is this what you are referring to?



One more example, which regretfully isn´t in the mathematical/physical language:

Let´s say there is an acoustic guitar and the lowest note it can play was 100Hz. You plug the string to make it vibrate at 100Hz and a certain amplitude and you need some ammount of mechanical energy to do so.
Now you press the string down in the middle to create a 200Hz frequency when being plugged. When oscillating at 200Hz the string does have to move double as much per second, at double the speed at least - so if you want it to oscillacte at same amplitude as at 100Hz you´ll have to bring up double the mechanical energy at least, maybe even four times as much.
To make it oscillate with same amplitude at 400Hz you´ll need four times the mechanical energy at least, at 800Hz its 8 times at least, at 1600Hz its 16 times, at 3200Hz its 32 times and at 6400Hz it was 64 times at least.

This would mean that playing a high note on an acoustic guitar would take the player 64 times the force at least to play this high note at same volume, if nature of soundwaves was constant amplitude - which it is not.

Playing a high note having the same volume on a guitar does not take 64 times the force, but about the same.
Therefore i conclude that nature of soundwaves is not constant amplitude but velocity.



I will agree that it is not in any mathematical/physical language which I know.

Phil
Yes.
After this example of the acoustic guitar there was a question for you .

josephazannieri
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Re: 78 noise

Post by josephazannieri » 15 Aug 2019 21:39

Yo Phil and H. Callahan and other noisy people:

I was under the impression that frequency and wavelength of sound were related according to the following formula, where F= Frequency, L = wavelength (can't get the lambda symbol) and V = speed of sound. V = FL.

There was a time where I would do a "speaker science" lecture for AP high school physics students in Clyde, Ohio. I did a demonstration with a small speaker where I would play music through it without a baffle and then drop an open manila folder with a circular cutout of cone size over it. The students would immediately notice that the low frequencies in the music reappeared. We would then use the formula V = FL to determine the cutoff frequency of the folder, and run a signal generator through the speaker, and the students would readily notice that the volume from the speaker dropped off roughly around the computed frequency.

My little gimmick was that I would ask the physics teacher to declare the speed of sound in Clyde, Ohio on that particular day, and it would usually come in somewhere around 1130 feet per second, based on elevation and temperature. On any particular day in Clyde, Ohio, the speed of sound is a constant which can be used to compute the wavelength of a particular sound. On this point I agree with H. callahan. The point of this digression is that as the frequency gets higher, the wavelength gets shorter. A 100 Hz tone has a wavelength of about 11.3 feet, and a 200 Hz tone has a wavelength of about 5.65 feet, at least in Clyde, Ohio. So, the length of the guitar string necessary to play the note has nothing to do with the wavelength of the note.

The frequency produced by the string has to do with the thickness of the string and how tight it is stretched between the guitar nut and the bridge, and, of course, the length of the string that is allowed to vibrate. On an acoustic guitar, the volume of the sound is affected primarily by the resonance of the guitar top and the vibrations that build within the body of the guitar, and less by how forcefully you pluck it. If you really pull the string, what you get is a really sharp attack and a gradual fade out. If you pluck gently, there is an attack, but it is less sharp, and more in line with the slow fade out. Also, playing a high note on a guitar involves using a finer string, which naturally vibrates at a higher frequency. If you are playing very high notes, you will notice that there is less reinforcement from the guitar body. So, the example of a guitar is not a good one.

A loudspeaker is a better example, because you can get a demonstration of the relationship between frequency and excursion that is easy to experience. Just set a frequency on an audio generator, say 500 Hz, and pick a volume. Touch the cone of the speaker with your index finger. You will feel a slight tingle in your finger. Then drop to 100 Hz at the same volume setting, and touch the cone again. You will feel a greater tingle because the excursion is greater. Then go down to 50 Hz at the same volume setting. If your volume is high enough, you may even see the motion of the cone at that low frequency. At some point around 50 Hz, depending on the speaker's characteristics, you may hit the cone resonant frequency, and at that point the speaker will just begin to jump around wildly, so the experiment will no longer be a good demonstration. But, in general, the higher the frequency, the smaller the excursion for the same volume.

Of course I am following my usual storytelling and excursive nature. Why use ten words when ten thousand are so much more fun to write? And good luck to all from that uneconomical old guy,

Joe Z.

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Re: 78 noise

Post by Coffee Phil » 15 Aug 2019 22:46

Hi Joe,

I do not have great experience as a speaker designer, but let me share my understanding of moving coil speakers. These speakers are highly inefficient. The voice coil impedance (above resonance) is largely the DC resistance, hence the current through the coil and the force it exerts on the cone is proportional to the applied voltage. I think the bulk of the remaining force acting on the coil is the mass of the cone. The acceleration of the cone is therefor proportional to the voltage. I believe that the pressure of the sound wave being launched by the cone is proportional to the acceleration of the cone. The result is that the sound pressure is proportional to the applied voltage.

I realize the above explanation is pretty grunt, but keep in mind I am a very amateur speaker tinkerer.

Now in the case of an acoustic cutting head there are several forces acting on the diaphragm. 1. The sound pressure times the area. 2. The spring force of the suspension (Hooke’s law). The force is proportional to displacement within the elastic limit. 3. The force from accelerating the mass of the structure. F=MA. 4.The force from the cutting stylus cutting through the wax. This one is more complicated but I would guess it is like viscous friction.

As the frequency moves through the audio frequency range. The motion of the stylus in response to the sound pressure will go from displacement to velocity then to acceleration as the opposing forces to pressure change in dominance in response to frequency.

From my experience with acoustic cut records, the modulation over most of the useable frequency range appears to be constant amplitude (displacement).

Digging out a clear answer to this from period literature is not proving to be easy for me.

Phil

josephazannieri wrote:
15 Aug 2019 21:39
Yo Phil and H. Callahan and other noisy people:

I was under the impression that frequency and wavelength of sound were related according to the following formula, where F= Frequency, L = wavelength (can't get the lambda symbol) and V = speed of sound. V = FL.

There was a time where I would do a "speaker science" lecture for AP high school physics students in Clyde, Ohio. I did a demonstration with a small speaker where I would play music through it without a baffle and then drop an open manila folder with a circular cutout of cone size over it. The students would immediately notice that the low frequencies in the music reappeared. We would then use the formula V = FL to determine the cutoff frequency of the folder, and run a signal generator through the speaker, and the students would readily notice that the volume from the speaker dropped off roughly around the computed frequency.

My little gimmick was that I would ask the physics teacher to declare the speed of sound in Clyde, Ohio on that particular day, and it would usually come in somewhere around 1130 feet per second, based on elevation and temperature. On any particular day in Clyde, Ohio, the speed of sound is a constant which can be used to compute the wavelength of a particular sound. On this point I agree with H. callahan. The point of this digression is that as the frequency gets higher, the wavelength gets shorter. A 100 Hz tone has a wavelength of about 11.3 feet, and a 200 Hz tone has a wavelength of about 5.65 feet, at least in Clyde, Ohio. So, the length of the guitar string necessary to play the note has nothing to do with the wavelength of the note.

The frequency produced by the string has to do with the thickness of the string and how tight it is stretched between the guitar nut and the bridge, and, of course, the length of the string that is allowed to vibrate. On an acoustic guitar, the volume of the sound is affected primarily by the resonance of the guitar top and the vibrations that build within the body of the guitar, and less by how forcefully you pluck it. If you really pull the string, what you get is a really sharp attack and a gradual fade out. If you pluck gently, there is an attack, but it is less sharp, and more in line with the slow fade out. Also, playing a high note on a guitar involves using a finer string, which naturally vibrates at a higher frequency. If you are playing very high notes, you will notice that there is less reinforcement from the guitar body. So, the example of a guitar is not a good one.

A loudspeaker is a better example, because you can get a demonstration of the relationship between frequency and excursion that is easy to experience. Just set a frequency on an audio generator, say 500 Hz, and pick a volume. Touch the cone of the speaker with your index finger. You will feel a slight tingle in your finger. Then drop to 100 Hz at the same volume setting, and touch the cone again. You will feel a greater tingle because the excursion is greater. Then go down to 50 Hz at the same volume setting. If your volume is high enough, you may even see the motion of the cone at that low frequency. At some point around 50 Hz, depending on the speaker's characteristics, you may hit the cone resonant frequency, and at that point the speaker will just begin to jump around wildly, so the experiment will no longer be a good demonstration. But, in general, the higher the frequency, the smaller the excursion for the same volume.

Of course I am following my usual storytelling and excursive nature. Why use ten words when ten thousand are so much more fun to write? And good luck to all from that uneconomical old guy,

Joe Z.

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Re: 78 noise

Post by Bob Dillon » 16 Aug 2019 00:53

Re : Period literature and acoutical recording. I think much of what they did in acoustical recording days was empirical, rather than based on much scientific theory. There aren't papers to give us enlightenment on the subject because there weren't many written and what was there was likely thrown on the trash heap decades ago.

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Re: 78 noise

Post by H. callahan » 16 Aug 2019 06:20

Coffee Phil wrote:
15 Aug 2019 18:45
Hi H. callahan,

Sorry, I guess I thought the question was rhetorical.

OK, there are several statements there.

First I believe you are saying that if you have guitar string which is tuned to 100 Hz, then shorten it to where it is tuned to 200 Hz. To achieve the same amplitude of vibration two times the energy will have to be stored in it at 200 Hz than required at 100 Hz. To that, I don't know the answer.

From the above you conclude that by nature sound waves are constant velocity as opposed to constant amplitude. I have no idea what might be meant by constant amplitude sound waves other that sounds of the same volume. The velocity of propagation of sound is ~ 1100 ft/second at sea level and I don't think that is a strong function of frequency, so I would say sound waves have constant velocity.

How any of the above relates to how a diaphragm in an acoustic cutting head responds to sound pressure of varying frequencies so far escapes me.

Phil
Now that you kindly went into my example we finally can go on.

If i understand you correct, you also assume nature of soundwaves to be constant velocity. So, to again use the example of the acoustic guitar, a 100Hz vibration of a string having the same volume as a 200Hz vibration of a string will have double the amplitude.
Meaning though both frequencies, 100Hz and 200Hz, have the same volume, the string vibrating at 100Hz does move double the distance left and right while vibrating than the string vibrating at 200Hz.

It can´t be any other way, because vibrating at same amplitude but double the frequency should take more energy, than vibrating at lower frequency but same amplitude. But as it does not take double the force to pluck a 200Hz tone out of a guitar having the same volume like a 100Hz tone, nature of sound must be constant velocity.

So my next question, please to be answered, is:

The strings of the guitar now will set the air molecules into motion, by that the soundwave created by the guitar will spread into the room, or wherever the guitar is played.
In what way will these air molecules now be set into motion? Will they:

a: vibrate at same amplitude very frequency, assuming each frequency being played at same volume

b: vibrate at greater amplitude at low frequencies and fewer amplitude higher frequencies - assuming low and high frequencies being played at same volume

c: vibrate at lower amplitude at low frequencies and higher amplitude at high frequencies, assuming low and high frequencies being played at same volume?

H. callahan
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Re: 78 noise

Post by H. callahan » 16 Aug 2019 06:41

josephazannieri wrote:
15 Aug 2019 21:39
Yo Phil and H. Callahan and other noisy people:

...
...

A loudspeaker is a better example, because you can get a demonstration of the relationship between frequency and excursion that is easy to experience. Just set a frequency on an audio generator, say 500 Hz, and pick a volume. Touch the cone of the speaker with your index finger. You will feel a slight tingle in your finger. Then drop to 100 Hz at the same volume setting, and touch the cone again. You will feel a greater tingle because the excursion is greater. Then go down to 50 Hz at the same volume setting. If your volume is high enough, you may even see the motion of the cone at that low frequency. At some point around 50 Hz, depending on the speaker's characteristics, you may hit the cone resonant frequency, and at that point the speaker will just begin to jump around wildly, so the experiment will no longer be a good demonstration. But, in general, the higher the frequency, the smaller the excursion for the same volume.

Of course I am following my usual storytelling and excursive nature. Why use ten words when ten thousand are so much more fun to write? And good luck to all from that uneconomical old guy,

Joe Z.
Thank you for your comment.
I´m aware that an acoustic guitar isn´t an ideal example, because of resonances of the guitar body, but its the first example Coffe Phil decided to go into. I brought up the example of a speaker before, but Coffe Phil did not answer to this post of mine.

Apart from that i´m not talking about speed of sound. Coffe Phil started to talk about that, but speed of sound isn´t that important for my example. Let´s say the guitar, or the speaker, is played at constant temperature, humidity and atmospheric pressure in a dust-free room.

Anyway you are understanding what i´m trying to explain:
The excursion the diaphragm of a speaker does produce at same volume, will differ with frequency. The lower the frequency, the higher the excursion of the diaphragm and vice versa. Only i called it "amplitude" and not "excursion".
And this does mean that nature of soundwaves is constant velocity and not constant amplitude - which i´m trying to make Coffe Phil understand.

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Re: 78 noise

Post by Coffee Phil » 16 Aug 2019 17:22

Hi Bob,

I would expect that at the beginning of sound recording the design of the equipment was pretty much empirical however by the 1920s I believe there was some physics being applied to it. Clearly The book which you linked from 1929 has mechanical models and even relates mechanical things like mass and spring constants to their electrical equivalents. When these folks were developing electrical recording it is clear they were modeling the acoustic components so they could build the electrical devices to be somewhat compatible with them.

What makes the book difficult is that some of the terminology is different from what we might see today. Clearly they had the concept of constant amplitude, constant velocity, and constant acceleration cutting down. I even saw a graph in the book comparing them however the units on the axis were not familiar to me. Part of getting through the book is learning the language of the day.

Phil


Bob Dillon wrote:
16 Aug 2019 00:53
Re : Period literature and acoutical recording. I think much of what they did in acoustical recording days was empirical, rather than based on much scientific theory. There aren't papers to give us enlightenment on the subject because there weren't many written and what was there was likely thrown on the trash heap decades ago.

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Re: 78 noise

Post by Coffee Phil » 17 Aug 2019 01:54

Hi H. Callahan,

I believe that you drifted away from the topic of how the diaphragm and the rest of the cutting structure of a cutting head respond to varying sound pressure into a discussion of traveling sound waves. To me in that context constant amplitude would mean a tone of constant volume. The velocity of sound wave propagation in air at sea level is ~ 1100 ft/sec. It is a function of barometric pressure and temperature but for the most part constant enough to do sonar. All that said, fine, but not all that relevant to the behavior of an acoustic cutting head.

Next you got into a vibrating string. OK a vibrating string is an oscillating system with energy shifting from being stored in the elasticity of the string to the velocity of the mass of the string periodically. The energy in the mass of the string is given by E=M(Vsquared). 1/2 the string will have 1/2 the mass so that suggests that the shorter string will have the square root of 2 times the velocity. Integrate that over one cycle to get displacement. It has been a while since I had to do calculus so I’m not going to bother. But if you want the answer knock yourself out. This still is not revelant to the issue at hand.

In one of these posts I listed some of the forces acting on the diaphragm which will drive it’s motion. You might seek it out and try to understand it.

Phil



H. callahan wrote:
16 Aug 2019 06:20
Coffee Phil wrote:
15 Aug 2019 18:45
Hi H. callahan,

Sorry, I guess I thought the question was rhetorical.

OK, there are several statements there.

First I believe you are saying that if you have guitar string which is tuned to 100 Hz, then shorten it to where it is tuned to 200 Hz. To achieve the same amplitude of vibration two times the energy will have to be stored in it at 200 Hz than required at 100 Hz. To that, I don't know the answer.

From the above you conclude that by nature sound waves are constant velocity as opposed to constant amplitude. I have no idea what might be meant by constant amplitude sound waves other that sounds of the same volume. The velocity of propagation of sound is ~ 1100 ft/second at sea level and I don't think that is a strong function of frequency, so I would say sound waves have constant velocity.

How any of the above relates to how a diaphragm in an acoustic cutting head responds to sound pressure of varying frequencies so far escapes me.

Phil
Now that you kindly went into my example we finally can go on.

If i understand you correct, you also assume nature of soundwaves to be constant velocity. So, to again use the example of the acoustic guitar, a 100Hz vibration of a string having the same volume as a 200Hz vibration of a string will have double the amplitude.
Meaning though both frequencies, 100Hz and 200Hz, have the same volume, the string vibrating at 100Hz does move double the distance left and right while vibrating than the string vibrating at 200Hz.

It can´t be any other way, because vibrating at same amplitude but double the frequency should take more energy, than vibrating at lower frequency but same amplitude. But as it does not take double the force to pluck a 200Hz tone out of a guitar having the same volume like a 100Hz tone, nature of sound must be constant velocity.

So my next question, please to be answered, is:

The strings of the guitar now will set the air molecules into motion, by that the soundwave created by the guitar will spread into the room, or wherever the guitar is played.
In what way will these air molecules now be set into motion? Will they:

a: vibrate at same amplitude very frequency, assuming each frequency being played at same volume

b: vibrate at greater amplitude at low frequencies and fewer amplitude higher frequencies - assuming low and high frequencies being played at same volume

c: vibrate at lower amplitude at low frequencies and higher amplitude at high frequencies, assuming low and high frequencies being played at same volume?

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Re: 78 noise

Post by H. callahan » 17 Aug 2019 04:44

Coffee Phil wrote:
17 Aug 2019 01:54
Hi H. Callahan,

I believe that you drifted away from the topic of how the diaphragm and the rest of the cutting structure of a cutting head respond to varying sound pressure into a discussion of traveling sound waves. To me in that context constant amplitude would mean a tone of constant volume. The velocity of sound wave propagation in air at sea level is ~ 1100 ft/sec. It is a function of barometric pressure and temperature but for the most part constant enough to do sonar. All that said, fine, but not all that relevant to the behavior of an acoustic cutting head.

Next you got into a vibrating string. OK a vibrating string is an oscillating system with energy shifting from being stored in the elasticity of the string to the velocity of the mass of the string periodically. The energy in the mass of the string is given by E=M(Vsquared). 1/2 the string will have 1/2 the mass so that suggests that the shorter string will have the square root of 2 times the velocity. Integrate that over one cycle to get displacement. It has been a while since I had to do calculus so I’m not going to bother. But if you want the answer knock yourself out. This still is not revelant to the issue at hand.

In one of these posts I listed some of the forces acting on the diaphragm which will drive it’s motion. You might seek it out and try to understand it.

Phil
Ok, i´ll try another take. The main problem i see is that soundwaves created by any source are not contant amplitude. As josephazannieri said, the diaphragm of a speaker will have greater excursions at lower frequencies than at higher frequencies - when low and high frequency are of same volume.

This means the air molecules being set into motion by any soundwave also will vibrate at greater excursion at lower frequencies and smaller excursion at higher frequencies. If you now feed such a soundwave into the horn of an acoustic recording machine, the diaphragm of the recording head also will move at greater excursion at lower frequencies and at smaller excursion at higher frequencies.
I´m aware that there are resonant frequencies of the horn and the head, also that there is moving mass of diaphragm, lever bar and friction while cutting into wax - but even if the horn had no resonant frequency at all, if the horn did not have peaks and drops in FR, even if the head did not have resonant frequencies and if diaphragm and lever bar had no moving mass at all - even then the cut could not be constant amplitude, because the soundwave going into the horn is not constant amplitude but more or less constant velocity. All the things left out now, resonant frequency, moving mass etc. all mean losses. So all these undesireable effects only can worsen recording of sound by which it even less could be constant amplitude.

Now i tried to explain by going from the string of an acoustic guitar, into the soundwave this guitar produces, into an ideal acoustic recording machine, having no resonant frequencies, no moving mass etc. .

Still we don´t seem to coincide what excursion of air molecules a low frequency and a higher frequency at same volume will produce. As long as we don´t coincide you won´t be able to understand my theory of acoustic recording.
As i said before i regretfully cannot provide you physical explanation, but i know by experience that a low frequency will produce greater excursions than a higher frequency having the same volume (sound level). I tried to explain with the speaker, the disco and acoustic guitar, though an acoustic guitar isn´t a perfect example.

josephazannieri does understand what i mean, maybe he can explain to you.

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