Klarinet Archive - Posting 000176.txt from 1996/10

From: "Scott D. Morrow" <SDM@-----.EDU>
Subj: Re: CO2 influencing pitch
Date: Tue, 8 Oct 1996 15:28:55 -0400

>Ian Dilley wrote:
>
>>I don't think this is true. Surely its the speed of sound in the column of
>>gas inside the clarinet and probably inside the player that is relevant
>>here not the gas through which it travels to your ears. If you breathe in
>>helium and then speak your voice is higher pitched. You don't have to fill
>>the entire room with helium to get the effect.
>
>
>Ok, this is sound logic. Pitch is dependent, to some extent, upon
>atmospheric pressure. Also the density (?) or composition of the gasses
>through which the sound travels also has an affect on the sound (tone,
>pitch etc). We all breath in the air around us but the way or bodies use it
>is different. I may not breath out as much C02 as Ian and the pitch could
>be affected by this. I think, however, that unless the concentration of CO2
>is great, the pitch discrepancy would be negligible.
>
>Remember, I'm not a scientist, I just play one on TV.
>
>Steve.
>
>Steve Prescott

Actually, I just looked up the sound velocities for air and CO2 in the CRC
Handbook of Chemistry and Physics: the speed of sound IS different for the
two (air: 331.45 m/s; CO2: 259 m/s). Now the question: wouldn't this just
affect how QUICKLY the sound reached you and NOT the pitch?

-Scott

Scott D. Morrow
Department of Biochemistry
School of Hygiene and Public Health
Johns Hopkins University
(410)-955-3631

SDM@-----.edu