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Re: Granular synthesis and auditory segmentation
>[I say "roughly reflect", because half-wave rectification
>does subtly alter the form of interspike interval
>distributions and autocorrelation functions.
>The autocorrelation of a sinusoidal component has the
>form of a cosine of the same frequency; the autocorrelation
>of a half-wave rectified component has flattened troughs,
>but closely resembles that of the unrectified component
>near the peaks. The positions of peaks and troughs are
>unchanged by half-wave rectification. When you listen to
>a half-wave rectified pure tone, it does sound very
>slightly different in timbre, slightly buzzy, but the
>pitch is the same,so the pure tone and its rectified
>counterpart don't sound all that different. I think
>Didier is right, however, in insisting on factoring
>in the effects of cochlear filtering first -- there
>are simple thought experiments with waveforms having
>positive-negative asymmetries which nevertheless still
>sound the same when polarities are reversed. If we
>only listened to the positive parts of asymmetric
>waveforms, different polarities should sound different.]
... Didier's example of listening to a Halfwave Sine vs a Sine is
not equivalent to the transduction function provided by the
neural HALFwave action caused by a neural refractory period
when the acoustic waveform is of the opposite polarity.
... Basically, the Basilar/Tectonic membranes are mechanically
driven by the BIPOLAR Sine waveform which is THEN HALFwave
transduced WHILE the Inner Hair Cells undergo the FULLwave
mechanical motion of a FULLwave sinewave.
... This is NOT the same thing as providing a HALFwave
ACOUSTIC waveform as THAT sets-up a QUITE different
quiescent base-line (+/-) reference for the Basilar Membrane
than does a SINE wave.
... i.e., the EFFECT is HALFwave transduction into neural pulse
rates while the transduced mechanical MOTION is FULLwave.
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