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How is timbre in sound represented electronically or digitally?

post #1 of 49
Thread Starter 

Sorry if this is a no-brainer, but I just can't seem to find much info about this.. All sources only talk about a single wave, most often a sinusoidal wave, and never mentions how the situation is like when there is a complicated sound signal with lots of stuff going on (different timbres for example.)

 

Please correct me if I'm wrong, but to my understanding timbre is a product of many sound waves together (if it was an instrument, a fundamental of the instrument and related overtones, etc.). So we have many sound waves at the same time, together creating a sense of timbre. What I don't get is how this is recorded by a microphone with a diaphragm that only senses *one* instantaneous frequency and amplitude, and then transmitted electronically via voltage signals that also only has *one* value for frequency and one for amplitude at a given time, how does this actually carry complicated sound signals with timbre, and not only single sine waves?

 

This relates to the whole chain I guess, from mic to speaker.. I have a fundamental hole in my understanding of sound waves and I'm having a hard time finding info besides the usual sine wave intro....

 

Would love some explanation regarding this!:-)

 

j

post #2 of 49

TIMBRE= The quality of a sound that makes it distinct from others of the same pitch and volume. IMO the key to this is the word "A" sound, meaning one sound.  Now rethink this definition and you should come up with your answer...........PS, I'm not being a smart ass either!

post #3 of 49

This is a pretty decent description of tne elements of timbre

 

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/timbre.html

 

 

 

post #4 of 49
Quote:

Originally Posted by Jodles View Post

So we have many sound waves at the same time, together creating a sense of timbre. What I don't get is how this is recorded by a microphone with a diaphragm that only senses *one* instantaneous frequency and amplitude, and then transmitted electronically via voltage signals that also only has *one* value for frequency and one for amplitude at a given time, how does this actually carry complicated sound signals with timbre, and not only single sine waves?

 

Timbre is basically frequency response or, more accurately, the balance of several frequencies to each other. In a musical instrument there are usually also resonances that define its timbre. A resonance is not just a frequency peak, but the peak is usually narrow and has a time-based property that decays over time even after the source ceases. A cello has many such resonant peaks, and the number and strength and distribution of those peaks is what makes every cello sound different from every other cello.

 

As for a microphone diaphragm being able to represent only one frequency at a time, that is not true. Same for loudspeakers that can vibrate at several frequencies at once. When I used to teach recording I'd sway my hand to show the class how a diaphragm can move at multiple frequencies at the same time. The last time this came up in a forum I made this (silly) little video showing my hand moving as a speaker would:

 

http://www.ethanwiner.com/misc-content/2waves.wmv

 

--Ethan

post #5 of 49
Thread Starter 

Thank you all!

 

Ethan, that was exactly what I needed to see! Thank you very much! 

 

So, basically we can represent a sound signal with only one wave with waves within waves, sort of? (waves superpositioned to form one wave)? Is this how voltage is used to represent sound?

 

I have a feeling all this will make much more sense when we start learning Fourier analysis in my course...

 

Thank you again!

post #6 of 49

If this helps, I think of it like this- the microphones membrane moves in response to a complex set of pressure changes in the air. It produces a voltage that represents those pressure changes. We record those voltages and reproduce them, using the voltage to drive a speaker that will reproduce (hopefully accurately) those pressure changes, recreating the sound waves.

 

The wave form is only the electrical representation of the air pressure as it changes over time.


Edited by Budgie - 10/28/10 at 8:08pm
post #7 of 49
Quote:
Originally Posted by Budgie View Post

The wave form is only the electrical representation of the air pressure as it changes over time.


Exactly. Further, a guitar or piano string, or violin body or drum head etc, vibrates similarly to my hand movement in that little video. So the sound sources themselves produce a complex wave from a single element (the string or drum head) that vibrates at several frequencies simultaneously.

 

--Ethan

post #8 of 49

Everyone who has posted their thoughts on the original QUESTION needs to read the definition of the word TIMBRE, IMO.....way off base!

post #9 of 49

Quote:

Originally Posted by 9pintube View Post

TIMBRE= The quality of a sound that makes it distinct from others of the same pitch and volume. IMO the key to this is the word "A" sound, meaning one sound.  Now rethink this definition and you should come up with your answer...........PS, I'm not being a smart ass either!


You gotta be joking. 

 

 

 

edit: Ethan, love your vids! biggrin.gif


Edited by xnor - 11/3/10 at 4:03pm
post #10 of 49
Quote:
Originally Posted by EthanWiner View Post

 

Timbre is basically frequency response or, more accurately, the balance of several frequencies to each other. In a musical instrument there are usually also resonances that define its timbre. A resonance is not just a frequency peak, but the peak is usually narrow and has a time-based property that decays over time even after the source ceases. A cello has many such resonant peaks, and the number and strength and distribution of those peaks is what makes every cello sound different from every other cello.

 

As for a microphone diaphragm being able to represent only one frequency at a time, that is not true. Same for loudspeakers that can vibrate at several frequencies at once. When I used to teach recording I'd sway my hand to show the class how a diaphragm can move at multiple frequencies at the same time. The last time this came up in a forum I made this (silly) little video showing my hand moving as a speaker would:

 

http://www.ethanwiner.com/misc-content/2waves.wmv

 

--Ethan


Good stuff Ethan.  Thanks for that!  Hopefully my understanding of how I hear 'body' or fullness in relation to timbre is correlated to the various resonances in collaboration w/ the frequency peaks.  If I'm way off let me know.

 

So do we take FR and square response together to form timbre?  I'm sure that's an oversimplification on my part.


Edited by Anaxilus - 11/3/10 at 3:40pm
post #11 of 49

Timbre is simply frequency content - no more, no less.
 

--Ethan

post #12 of 49
Quote:
Originally Posted by EthanWiner View Post

Timbre is simply frequency content - no more, no less.
 

--Ethan


Then what measure would relate to the quality of a notes body, fullness or roundness?  That can't be FR sice I could have w phones w/ flat FR and one could sound thin or dry and the other lush and wet.

post #13 of 49

no two different models of headphones have similar enough frequency response to really sound the same in ABX comparison, even choice of frequency/weighting for level matching is a challenge

 

listening level - Fletcher-Munson "loudness effect" and detailed frequency response are the main determinants of differing "sound" in headphones

 

amplifier output impedance can change the FR of (some) headphones

 

clipping may be more common than many want to admit - the "Loudness Wars" levels of compression and hard amplifier clipping added distortion harmonic content may be responsible for perceptually distorted "FR"

 

wide impedance and sensitivity differences between headphone models make the likely-hood of of the above affecting the casual "just listen" comparison very high 


Edited by jcx - 11/4/10 at 2:17pm
post #14 of 49

Quote:

Originally Posted by xnor View Post

Quote:


You gotta be joking. 

 

 

 

edit: Ethan, love your vids! biggrin.gif

What are guy's talking about? Look the Word Up!!  Timbre the term used to denote the tone color of a specified instrument or piece of music, for example, "rough" or "bell-like." The concept of timbre is useful when trying to describe music in words, for instance, a fiddle has a different timbre than a trumpet.......or Timbre [pronounced tamb'r] Tone quality, characteristic instrumental sound. Not especially a Jazz term, but note that timbre is one of the basic dimensions of music along with rhythm, melody and harmony. or Timbre Timber (pronounced "tam'-ber") is what makes one thing sound different from another, even people's voices. It is also known as tone color. The timber of a violin is very different than the timber of a flute, so they are easy to tell apart. Even when they are playing the very same note, it is easy to hear both of them. The buzzing of the tissue paper in the kazoo does nothing but just change the timbre of your voice by adding additional vibrations to the notes you hum.

PS---SOUND IS SOUND, it does not matter if it's  represented electronically or digitally?
 

post #15 of 49
Quote:
Originally Posted by Anaxilus View Post

Then what measure would relate to the quality of a notes body, fullness or roundness?  That can't be FR sice I could have w phones w/ flat FR and one could sound thin or dry and the other lush and wet.

 

Anyone?
 

Quote:
Originally Posted by 9pintube View Post

Quote:

What are guy's talking about? Look the Word Up!!  Timbre the term used to denote the tone color of a specified instrument or piece of music, for example, "rough" or "bell-like." The concept of timbre is useful when trying to describe music in words, for instance, a fiddle has a different timbre than a trumpet.......or Timbre [pronounced tamb'r] Tone quality, characteristic instrumental sound. Not especially a Jazz term, but note that timbre is one of the basic dimensions of music along with rhythm, melody and harmony. or Timbre Timber (pronounced "tam'-ber") is what makes one thing sound different from another, even people's voices. It is also known as tone color. The timber of a violin is very different than the timber of a flute, so they are easy to tell apart. Even when they are playing the very same note, it is easy to hear both of them. The buzzing of the tissue paper in the kazoo does nothing but just change the timbre of your voice by adding additional vibrations to the notes you hum.

PS---SOUND IS SOUND, it does not matter if it's  represented electronically or digitally?
 


Are you saying Timbre is unrelated to Frequency Response?  You don't think that's what gives the notes their color?

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