What's different in a soundwave when I say "AAA" and "OOO"?

[CaptainPanic]

I understand sound waves: amplitude and wavelength (or frequency) are rather simple concepts. I understand how sounds travels (in a straight line, and deflected or absorbed by objects).

 

I also read that our vocal cords produce many harmonics, which I suspect is what makes everybody's voice unique.

 

What I don't understand is how you can explain the difference between pronouncing an "A" and an "O", and both at the same frequency. I can see that the mouth makes a different shape, but I fail to understand how the sound waves are affected by the shape of the mouth (amplitude or wavelength of the set of harmonics are changed I guess... since there isn't much else to sound, is there?)

 

I don't think music can be involved in this discussion easily, because I see the differences between instruments more like differences in voices (harmonics) rather than letters

 

Just a question that I cannot answer... for entertainment value

[DrP]

Someone else can probably give a better answer than I, but to take a guess from distant memory (for entertainment value ), I think it has something to do with the shape of the wave as well as the amplitude and wavelength.

 

Like in your example I would guess the AAA has a sharper/squarer wavefront than the softer/rounder OOO. More 'attack' on the AAA.

 

(I stand to be corrected by someone who actually knows something about this! )

[Sisyphus]

Yes, it is the shape of the wave, called timbre. It's partly harmonics (composite waves), but not totally.

[CaptainPanic]

Doh!

Im my perfect world, waves are simply a sine (or cosine). I could have know perhaps that the shape of the wave itself can also change.

 

Does anyone know how it's being changed? I'm assuming that the vocal cords do the same trick for both A and O, and that the shape of the mouth then changes the shape of the wave. But that assumption doesn't come with a background or explanation (so it's useless).

[insane_alien]

do you have a microphone? if you do go get audacity and record yourself saying these things and zoom in on the wave form.

[Kyrisch]

Well the waves interact with your mouth and diffract about your lips, so it would seem that they could easily change the shape of the wavefront.

[swansont]

Once the shape of the wavefront has changed from being a sine, you will have harmonics. You get other shapes by adding together different frequencies (Fourier components) with the appropriate amplitude.

[Severo]

Timbre, and also normaly when you say AAA, it is a higher tone

which means it's a higher frequency.

and when you say OOO, normaly it's a lower tone.

which means lower frequency

 

frequency = tone

amplitude = "strenght" ( how loud it is)

[Mike Dubbeld]

This is specifically covered (Ahhhhh and Ohhhh) in the book Who is Fourier on p143 and elsewhere. The whole book is about Fourier analysis of waves and how a spectrum FFT analyzer works. When you hear the note C on a piano it is clearly distinguishable from the same note C on a flute. The difference is called the Quality or Timbre. The 2 instruments have the same fundamental frequency but the sounds are different because of the different amounts of the various harmonics. ANY form (geometry) can be represented/constructed by a Fourier synthesis of sine waves and likewise any form can be deconstructed into it a number of simple waves of various amplitudes and frequencies (Fourier analysis). The larynx in the throat and voice box we use to create rarefactions and compressions of air molecules (longitudinal waves) which can be represented mathematically as sinewaves. Intstead of Quality or Timbre I like to call the complex waves produced on a FFT (Fast Fourier Transform) Analyzer their Fourier Fingerprint. Every 'form' in the universe/conglomeration of atoms and molecules having a rigid structure has a unique Fourier fingerprint which I also call its 'real' name. In other words, every 'solid' shape has a form. Every form (geometry) has a corresponding set of Fourier component waves into which it can be broken down into. The form can be considered simply a complex wave made up of a large number of simple sinewaves (each of which having their own amplitude/coefficients and frequencies) such that when added together they produce the form/geometry. This entire subject goes much further than anyone on this forum might even likely to suspect. It can be taken into quantum mechanics as well using spherical waves (Nick Herbert Quantum Reality).

 

As 3-dimenisonal creatures with our sole experience from the senses being in 3-d, we cannot visualize more than 3 dimensions. Yet everyone knows mathematically there is no reason we cannot go beyond 3 dimensions. As strange as it may seem, every frequency can be considered a dimension in Fourier series that is orthogonal to other dimensions. (orthogonal being perpendicular to) Thus, a vector with 8 dimensions can be represented as 8 waves each with a different frequency and the Fourier coefficients represtative of the amplitude of the vector in that dimension. We can visualize n dimensions as n waves to think about intuitively.

 

For example:

Suppose I have tomato juice as having A amount of tomato; B amount of celery; C amount of lettuce; and D amount of cabbage. Now if I wanted to plot this

f(tomato,celery,lettuce,cabbage) I would need 4 dimensions. Leave off the cabbage (dimension). Use the coefficients A,B,C as the amplitude of a vector in the 3 component directions having a resultant vector in 3-d space along the x,y and z axes whose 'shadow' on each of the planes represents its component. The resultant vector would have a taste unique from another brand that also uses tomato,celery and carrot but in the amounts D,E and F. D, E and F being again the vector components in each of the cardinal directions on a right-handed Cartesian coordinate system. Since it has different component amounts of the same ingredients it tastes different than the other brand. Its resultant vector points in a different direction and magnitude also. But if you want to plot more than 3 variables (vegtables) you can't do it. But you can assign a frequency to each vegtable for any number of vegtables with A,B,C,D....n Fourier coefficients and add the waves together and visualize that!

 

The above example is shown in great detail in the book Who is Fourier. If you have had calculus and done some vector things, the whole book reads as easy as a comic book (complete with cartoon characters!). They demonstrate what I said above much more clearly. They show Ahhh and Ohhh and other sounds as produced on a FFT specturm analyzer. They also show how this leads to the QFT Heisenberg Uncertainty Principle Heisenberg matrix vs Schrodinger wave - a mapping showing the 2 to be identical in much the same way as vectors and waves above.

[alan2here]

A square wave can be created by finding the average of the correct set of sin waves. Therefore a square wave can be thought of as being a set of sin waves at the correct frequencies and offsets.

 

Wave shape is another way of saying harmonics, although a square wave is a simple shape that creates complex harmonics and simple pasterns of harmonics create complex waves. Each way of looking at the wave is just as useful but different.

 

The method of getting from a wave shape to a series of harmonics that could be used to create it or more accurately to the volumes of a set of incremental frequencies that would create that wave shape is called spectrum analysis and it (although I hope someone in about to prove me wrong) is the only sensible way of analyzing sound.

[catman529]

Yeah, I don't know a whole lot about sound but have figured out the basics by editing sound waves manually using GoldWave - the waves for an "AAA" and "OOO" sound have different "shapes". The "OOO" would be closer to a sine wave (but definitely not near a pure sine wave).

 

If you want to take recordings and look at the shape of the sound waves, this can be done with GoldWave - by narrowing your selection to a very narrow strip a few times and pressing the "Sel" (selection) button each time to expand the narrow selections. You can get down to a point where the sound waves are represented by a line, and you can modify the waves with your mouse.