ers
Walter Knapp wrote:
> Paul Dickinson wrote:
>
>>Walt, I think you are describing is what composer Marianne Amacher
>>calls "the third ear"- acoustical intermodulation at relatively high
>>amplitude produces sum and difference frequencies, which don't exist
>>in either (or any) of the sources. In a sense, it is an error in the
>>human auditory system.
>
>
> And on sonogram, and waveform? Not all sounds produced by animals are
> exactly the same frequency or in exact phase. They are not lab
> instruments. IT DOES EXIST!!
And as a farther note, this occurs on sounds that are only recorded
faintly. Not just loud ones. Often the out of phase call is a entirely
different distance than the first call, One can be a lot fainter than
the other and it still works. All can be faint calls.
So, it's not caused by the sounds being loud (at the mic anyway). And
any theory that will only happen when the signal is strong is not a
explanation.
I would suggest going outside early next spring and listening to a nice
group of american toads, or whatever long triller you have locally. Our
ears do not pick it out as well as sonograms and such like do, but they
do pick it up.
Out of phase, frequency differences like this are not errors at all,
they are quite normal. If that messes up our view of how animals call
then our view is wrong.
Walt
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