[sdiy] Phase shifts and instantaneous frequency

[Ian Fritz]

At 06:02 PM 7/15/2008, Aaron Lanterman wrote:

>>The 1 Hz modulation comes from beating of the 101 Hz and 100 Hz
>>signals.
>
>That might be the case, but the perceived beat seems to be more easily
>explained by simply noting it's a wave that's periodic with a period
>of 1 Hz.

Again, the power spectrum is constant in time.  So doesn't linear signal 
theory say you would not hear beats?  That's the first-order picture, that 
the ear does a linear Fourier analysis.  And if you listen at a low volume 
level you don't hear the beats, whereas they are very pronounces at high 
volume levels.  How do you explain that with a linear theory?  *Any* linear 
theory?

And if you present the signals separately to the two ears you don't hear 
the beats, either.


>There might be weird complicated intermodulations going on in
>the ear, but we don't _have_ to fully resort to them to explain what's
>happening in that particular example.

I think you do, sorry.  :-)


   Ian