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Can you answer this?

post #1 of 28
Thread Starter 

I was having a discussion with a coworker recently about lossless vs lossy. He argued that the *only* thngs missing in a high bit rate lossy mp3 were frequencies that most people cannot hear anyway. While I know that it is not quite that simple, it got me thinking about a few things, one of which is the following scenario:

 

Suppose you have one recording of nothing but a 1000 hz tone (Recording A). Now say you have another recording of a 1000 hz tone, but the second one gives the listener a strong perception of depth (Recording B). Since sound itself is analog, which means that it is nothing but movement of air at various frequencies, it would follow that the the two recordings are different because of the presence (or lack of) additional frequencies that give the feeling of this depth. Yet the recording is still nothing more than a 1000 hz tone. So, my question is this - what is it exactly that gives recording B the sense of depth? And, are these differences considered "disposable" by a lossy codec and being thrown away? And please - I would like to not get into the old lossy vs lossless debate. I just am very curious.

post #2 of 28

i am no expert...but just my opinion.  I don't think that it is possible.

my logic tells me that two different recordings of 1000hz tone should sound exactly the same.

like you said,if a perception of depth is cuased as a results of certain frequencies,than how can it be that only one frequency can sound different in both cases.   

post #3 of 28
Thread Starter 

Ok, to clarify my scenario, let's say that when recording B was made, the mike was placed much farther away from the source in order to give the sense of depth. Still a 1000 hz tone, only differing in microphone placement.

post #4 of 28
post #5 of 28
Quote:
Originally Posted by FlatNine View Post

Ok, to clarify my scenario, let's say that when recording B was made, the mike was placed much farther away from the source in order to give the sense of depth. Still a 1000 hz tone, only differing in microphone placement.



ok..so you are talking of the same frequency but with a different in volume (because the mic was farther away...) am i right?      if you place the mics at two diffferent places there must be a different in volume,am i wrong here?

post #6 of 28
Thread Starter 
Quote:
Originally Posted by plonter View Post





ok..so you are talking of the same frequency but with a different in volume (because the mic was farther away...) am i right?      if you place the mics at two diffferent places there must be a different in volume,am i wrong here?



Possibly, but even if the listener adjusted the volume, the depth thing would still be perceptible. Exactly what causes that is what I am trying to understand.

post #7 of 28
Quote:
Originally Posted by FlatNine View Post





Possibly, but even if the listener adjusted the volume, the depth thing would still be perceptible. Exactly what causes that is what I am trying to understand.


are you sure about this?  maybe if the listener adapts the volume the result will be the same.   the second possibilty is that if,like you said,the different in depth will still be there even after the listener has adapted the volume,this  can be as a result of the original recording,where the volume was different.  maybe if the listener adapts the volume himself it would not matter,and the original recording volume is what counts.

 

again,this is interesting me so i am just giving my thought.  i have no scientiffic knowledge what so ever about those things.   and my logic tells me that frequency is a frequency all the time and should sound the same if recorded in the same volume.

let's see what others have to say about this.


Edited by plonter - 6/5/10 at 8:34am
post #8 of 28

You're missing the fundamentals. Either you have a recording of a X KHz tone or you do not. Moving the mic farther away from the generator will only decrease the volume. Or, you have various errors introduced by the analog recording, and you don't really have a pure X KHz tone. End of discussion.

post #9 of 28

you know..I just thought of something.  let's say i am recording the same frequency in both the recordings with the same volume and placement of recording gear,when the only different is the brand of the mic.   will it sound the same?  and if not,how can we explain differences in sound between different gear/brands?

or the same question only with headphones, can we say that two headphones should sound identical  if they have exactly the same frequency response?  what else can influence the final sound except from frequency response?


Edited by plonter - 6/5/10 at 9:02am
post #10 of 28
Thread Starter 

I'm not trying to be a jerk here, and it could be that I am missing something here. But given two recordings, one with a sense of depth, the other without, what is it that is present in the recording with depth that gives it that sense of depth? Let's forget about the 1khz scenario for now.

post #11 of 28
Quote:
Originally Posted by plonter View Post

you know..I just thought of something.  let's say i am recording the same frequency in both the recordings with the same volume and placement of recording gear,when the only different is the brand of the mic.   will it sound the same?  and if not,how can we explain differences in sound between different gear/brands?

or the same question only with headphones, can we say that two headphones should sound identical  if they have exactly the same frequency response?  what else can influence the final sound except from frequency response?


In the real world, different mics will likely have different diaphragms (mass, damping, resonance) and electrical circuitry, and will pick up the same source differently. It's similar for headphones, but instead of picking up sounds differently, the diaphragms reproduce sounds differently. The frequency response gives your sound, but lots of things affect frequency response from a technical point of view.

 

Quote:
Originally Posted by FlatNine View Post

Possibly, but even if the listener adjusted the volume, the depth thing would still be perceptible. Exactly what causes that is what I am trying to understand.


The perception of depth is caused by decay in frequency and amplitude, and further, different frequencies decay at different rates. In your 1 kHz tone example, after travelling x metres, the sound is no longer a 1 kHz tone at the same amplitude. As you change the distance, you will get spectrum/amplitude profiles that vary.

 

Our brains are pretty much tuned by our environment (assuming you haven't been plugged into earphones from the day you were born), and expect sound to decay in a certain manner. We learn to associate this decay with distance, which forms our perception of depth.


Edited by radioactive28 - 6/5/10 at 9:33am
post #12 of 28
Quote:
Originally Posted by radioactive28 View Post


In the real world, different mics will likely have different diaphragms (mass, damping, resonance) and electrical circuitry, and will pick up the same source differently. It's similar for headphones, but instead of picking up sounds differently, the diaphragms reproduce sounds differently. The frequency response gives your sound, but lots of things affect frequency response from a technical point of view.

 



thank you for the explanation.  I just want to make sure i understood correctly.

so the frequency response will be the same but will sound different (because of other factors) or will the frequency responce will not be the same due to other factors.

post #13 of 28
Thread Starter 
Quote:
Originally Posted by radioactive28 View Post


In the real world, different mics will likely have different diaphragms (mass, damping, resonance) and electrical circuitry, and will pick up the same source differently. It's similar for headphones, but instead of picking up sounds differently, the diaphragms reproduce sounds differently. The frequency response gives your sound, but lots of things affect frequency response from a technical point of view.

 


The perception of depth is caused by decay in frequency and amplitude, and further, different frequencies decay at different rates. In your 1 kHz tone example, after travelling x metres, the sound is no longer a 1 kHz tone at the same amplitude. As you change the distance, you will get spectrum/amplitude profiles that vary.

 

Our brains are pretty much tuned by our environment (assuming you haven't been plugged into earphones from the day you were born), and expect sound to decay in a certain manner. We learn to associate this decay with distance, which forms our perception of depth.

 

Fascinating, and just the kind of information I was looking for. Thanks!
 

post #14 of 28

Radioactive is right.  If you have two files with purely a 1khz tone, they will sound exactly the same, you can't have one the has more "depth" than the other.  If you were playing a 1khz on a speaker and recorded it from different places, then you wouldn't have just a pure 1khz tone.  You'd have the echo and the effect of the room on the tone.  Moving it farther away gives a different effect on the sound.

post #15 of 28
Quote:
Originally Posted by xxbaker View Post

Radioactive is right.  If you have two files with purely a 1khz tone, they will sound exactly the same, you can't have one the has more "depth" than the other.  If you were playing a 1khz on a speaker and recorded it from different places, then you wouldn't have just a pure 1khz tone.  You'd have the echo and the effect of the room on the tone.  Moving it farther away gives a different effect on the sound.



yep..exactly my thoughts.  our perception of depth,and maybe other "sound effects" (not sure about soundstage) is all a matter of certain frequencies playing in the recording. and when it is only one lonely frequency,those effects can't be percieved.

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