AW: [sdiy] some observations : audibility of phase distortion

[Tom May]

"TIm Daugard" <daugard at sprintmail.com> writes:

> My understanding from lots of physics books is that the speed of sound is the
> same for all frequencies. It varies with material or air i.e. speed through
> metal is faster than speed through air. It varies with air temp and pressure.

According to http://www.sasked.gov.sk.ca/docs/physics/u5b22phy.html:

  The speed of sound in a gas depends on the temperature, molecular
  weight, and molecular structure, but not on the pressure of the gas.

They start with "the Newton-Laplace equation for the speed of sound in
a gas" and apply the ideal gas law to achieve this result.  Any
variations due to pressure (or frequency?) would be second-order
effects.

This agrees with what I've heard to be true about mach numbers
vs. altitude: mach 1 doesn't vary with pressure changes at altitude,
it varies with temperature changes at altitude.

Speed of light on the other hand does vary with frequency and medium,
that's tied up in how lenses and rainbows work.

Tom.