Re: Doppler Distortion - Fact or Fiction?

From: Bob Cain (arcane_at_arcanemethods.com)
Date: 08/21/04 

Date: Fri, 20 Aug 2004 18:20:30 -0700

Richard Herring wrote:

> In message <cg1ibl0266t@enews4.newsguy.com>, Bob Cain
> <arcane@arcanemethods.com> writes
>
> [big snip]
>
>>
>> Whatcha think?
>>
> I think you missed my point about the pressure being a linear function
> of piston displacement _evaluated at a retarded time which depends on
> the piston's position_.

Nope, I attempted to describe why it isn't correct in the
case of a piston in a tube. Another simple arguement for
the lack of any kind of Doppler distortion in that
situation, assuming SPL's are low enough to keep the air in
its linear regime, is that the radiation impedence seen by
anything driving the piston is identically the
characteristic impedence of the air, real and frequency
independant. Given that, where is there room for any error
in the process?

>
> All the physical processes are individually 100% linear, but the outcome
> is not.

Odd, that. I just don't understand how that could possibly be.

Bob 

-- 
"Things should be described as simply as possible, but no 
simpler."
                                              A. Einstein

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