Close-talking differential microphone arrays (CTMAs) are useful in
situations where the background noise level is very high because
they inherently suppress farfield noise while emphasizing desired
nearfield signals. One problem, however, is that the array has to
be placed as close to the desired source (talker's mouth) as
possible since the frequency response and level of a differential
nearfield array depend heavily on its position and orientation
relative to the source signal. In order to be able to utilize the
advantages of CTMAs for an extended range of microphone positions,
this contribution examines the possibility of tracking the
desired signal source by estimating its distance and orientation
angle. With this information, appropriate correction filters can
be applied adaptively which equalize unwanted frequency response
and level deviations within a reasonable range of operation
without significantly degrading the noise canceling properties of
differential arrays. A PC-based real-time implementation with
transducer calibration capabilities of this adaptive CTMA is
presented.
