Speed of Sound

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MtnBob

MtnBob

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Joined 2003
Anyone know a simple way to calculate the speed of sound at different altitudes? I always see it as 341-344 m/s at sea level, but I live at 2667 m (8750 ft). Is there enough differance to matter when it comes to audio calculations (esp dipole calcs)?
 
J

johninCR

Member
Joined 2004
Bob,

Don't even worry about it. With OB, the room and floor boundaries play a much more significant role that calculations, spreadsheets, etc. can be thrown out the window. I build only OB speakers and live at 1500m. The only calculation I ever use it to compute an estimated Fequal point and in room you always get more bass than that. That's the beauty of OB, no formulae etc to restrict you or tell you what to do.
 
Ron E

Ron E

Member
Joined 2002
What is left out of what has been discussed so far is humidity. Humidity can have an effect on sound velocity as well as temperature and pressure.

Download Claus Futtrup's DPC calculator. He has a few text files included in the package which detail how to calculate sound speed for varying pressure and temperature and humidity.
 
Ron E

Ron E

Member
Joined 2002
It is not a lot, as a first approximation it is easily neglectable compared to temperature. The effect is there, and it gets greater with increased temperature.

T in celcius
RH in percent (relative humidity or w/ws)
c=speed of sound in m/s

I have a tool to calculate:
T=0, Rh=0 - c=331.4
T=0, Rh=100 - c=330.8
so ~0.3% difference


T=40, RH=0 - c=354.8
T=40, RH=100 - c=347.9
so ~2% difference
 
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