3aSPa7. Adaptive noise cancellation with directional microphones.
Session: Wednesday Morning, December 4
Author: Gary W. Elko
Location: Acoust. and Audio Commun. Res. Dept., Lucent Technol., Bell Labs., 600 Mountain Ave., Murray Hill, NJ 07974
The use of adaptive noise cancellation in communication devices has now
been under investigation for more than two decades. Early studies predicted
large SNR gains that were rarely obtained when actual devices were tested in
typical acoustic noise environments. One of the problems encountered was
the lack of coherence between the ``noise'' sensor and the actual corrupting
noise signal. The measured low coherence values were most probably due to
time-varying multipath, multiple uncorrelated noise sources, and nonlinearities
in the signal and noise transmission paths. This talk will address the expected
noise cancellation that can be obtained by using directional microphones to
spatially filter the acoustic field into signal-plus-noise and noise channels.
Analytical results for spherically and cylindrically isotropic noise fields will
be shown and discussed.
ASA 132nd meeting - Hawaii, December 1996