rs
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.
>Gianni Pavan wrote:
>
>> I hope these notes may help in facing correctly with the aliasing
>>problems...
>
>I think before we start deciding the Nyquist frequency has something to
>do with it that it might be well to consider that I'm talking about the
>American Toad, or Southern Toad. Both call with a frequency below 2 kHz.
>That would be one sick system to fold to that level, immediately obvious.
>
>As I've noted, it's not aliasing, it's not Nyquist, or bad tweeters or
>any of those. Unless human ears have that error. It is, in fact, not a
>error at all, many natural sounds include phase interference, in fact
>quite a bit of phase interference is common in the natural environment
>even with a single call.
>
>Get away from the signal generators, get outside with no equipment and
>listen. Or if you insist on equipment, get outside and take your signal
>direct off the mic as it picks up the sounds.
>
>Walt
>
>
>
>
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--
Paul Dickinson
Film/Video Teaching Associate
UIC School of Art and Design
Ph. 312-996-0767
Fax 312-413-2333
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