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You're right, it doesn't. I was just quoting the explanation I got on the web, will have to look into it later, when I get back. |
moral of the story, don't listen to chemists trying to explain physics
My post above appears to be a valid proof that frequency does not change, i'll rewrite it with numbers. It requires no knowledge of wave equations and is based only on the definitions of velocity, period and frequency.
Let X1 rep. the initial time of the first crest of a wave is created
Let Y1 rep. the time the next creast is created.
Period is defined as the time between two successive crests of a wave, so initial period would be Y1-X1
Now, if the sound had to pass through n regions (ie different gasses) , each with a different length and propagation velocity, then the total time for the first crest to reach the end would be:
Xt= X1 + T1 + T2 + .... + Tn
where Tn is the time required for the wave to pass throughthe region. The wave propagates through any region at constant velocity, and we'll assume that the length of the region is fixed. (if it isn't, you'll get the doppler shift i described earlier) Therefore, Tn = Dn/ Vn, simply from the definition of constant velocity.
So Xt = X1 + D1/V1 + D2/V2 + ...+ Dn/Vn
Now you can do the exact same thing with the second crest.
Yt = Y1 + t1 + t2 +... + tn
Note that i used lowercase t's here, so not assuming its equal to T1 for the first crest. But since it is passing through the exact same regions, and each region has a fixed length and velocity, they do turn out to be the same:
Yt = Y1 + D1/V1 + D2/V2 +.... + Dn/Vn
So now calculate the final period:
Yt - Xt = (Y1 + D1/v1 + D2/v2 +....) - (X1 + D1/v1+ ....)
= Y1- X1
= initial period
QED
(frequency is simply the inverse of period, so it also can not change)
Note that you can have any number of regions of any length, the speed can be anything (well, greater than zero, much less than speed of light) and the frequency of the wave still does not change.
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This actually sounds more reminiscent of the explanation I got in physics class, so you are probably correct.
That said, if the same driver (your vocal chords) can produce a higher frequency when "submerged" in a lighter gas, couldn't the same concept still work for a driver "submerged" in a heavier gas, producing lower frequencies? I think it would still work. Perhaps the resonant frequency and other characteristics of the driver are all meant for "in air", and they all change in Xenon/Argon. Perhaps czilla wouldn't even need to pitch-shift the incoming frequency. |
I've already explained this in my previous posts. Your speech isn't produced by a "driver", it works on the principal of resonance. But drivers do not resonate, they only respond to the signal they are sent- any resonance in a driver is distortion, and a properly designed driver will have its resonance frequency outside its operating range.
AS i said earlier, you may be able to increase sensitivity and bandwidth slightly, but that's it.
And i've already explained that no speaker can be built entirely on resonance, since it only occurs at specific frequencies- your driver would literally only be able to produce "one-note bass"
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Yeah, but then you don't get the transition that I describe. So, not really a good experiment. |
My "experiment" is to be identical to what you just proposed, except i used headphones and you used speakers
It should clearly show whether there is any pitch change.....