Re: Stupid Audio Question

Glen Walpert wrote:
Shock
waves do not really go faster than the speed of sound (how can sound
go faster than sound?), they only go faster than the infintessimal
amplitude speed of sound.

If all you mean by "speed of sound" is "how fast this particular disturbance travelled from A to B", then you're right, but that isn't the usual (or useful) definition, because it only applies to the one case. The usual definition of a shock wave is one where the entropy density is significantly increased by its passage.

BTW, the speed of infinitesimal amplitude sound varies with the mean
molecular weight of the air, which changes with humidity (~.4%
increase dry to wet at STP). And the characteristic impedance of air
varies directly as infinitesimal amplitude speed * density, a function
of pressure, temperature and humidity.

Yes, all of which are very very constant on the time scales of sound waves (see subject line).

Back on your heads.

Cheers,

Phil Hobbs

.

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