On 30/05/2011 19:01, Fons Adriaensen wrote:
On Mon, May 30, 2011 at 05:54:12PM +0100, dw wrote:
It is the point at which it goes through zero as the phase goes through
180 degrees.
Now I'm puzzled... That frequency corresponds to a wavelength
of 2.6 meter, which is more than 10 times the size of a human
head. Which phase (or phase difference) goes through 180 degrees
at that frequency ?
Ciao,
For Xtalk cancellation, the intention is to get the blue line intended
for the contralateral ear (far, right ear) to cancel as far as possible
(by being equal and opposite) the green line intended for the near, left
ear, when both reach the right ear (mauve line) after the 3 sample delay
and attenuation of the head. When these two same signals vector sum at
the near ear the result should be a flat frequency response (top yellow
line). Of course this is only a computer model of the head, so it is not
likely to be quite as good in practice! At low frequencies this
corresponds to the signals being (nearly) 180 out of phase at the
speakers until I give up on flogging the speakers to death and swap to
driving them in phase. The above only applies to right or left channels
on their own. If the source is mono everything cancels during
convolution and the speaker drives are in phase and at a lower level
(lower yellow line).
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