VIRTUAL ACOUSTICS AND AUDIO
ENGINEERING Fluid Dynamics and Acoustics Group |
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In this system we do not attempt
to reconstruct the sound pressure at the eardrum exactly. It has been shown
that the main advantage of such an arrangement is that the rate of change
of the interaural cross-correlation (IACC) function with respect to head
rotations in a four channel system, with loudspeaker also placed behind
the listener, can be reproduced. Our goal in this case is to reconstruct
the accurate pair of HRTFs at the blocked ear canal when the head is rotated
at angles of ±50. In this animation we demonstrate the operation
of the cross talk cancellation by reproducing “1” at ear no. 1 and “0”
at all the others (this is achieved by multiplying the vector [1 0 0 0]T
with the cross-talk cancellation matrix H). We can notice the effect of
the cross talk cancellation on the robustness of head rotations: the zero
pressure in the right side is maintained when the head is rotated, and
on the left side a rapid change between “0” and “1” is achieved. Two conclusions
can be reached from this example: the use of four ears for calculation
of filters for a single listener proves very robust to head rotations and
can provide important cues for front and back discrimination. Secondly,
the 'sweet spot' is reduced in comparison to the 2x2 system presented in
the previous example. If the head is moved forward or backward the cross-talk
cancellation effect disappears.
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