27-10-2012, 11:23 AM
Implementing and Evaluating an Audio Teleconferencing Terminal with Noise and Echo Reduction
ABSTRACT
We have developed an audio teleconferencing terminal for use in noisy office environments. The terminal has an
acoustic-echo cancellation filter in the time domain, noise and echo reduction in the frequency domain, and variable loss
insertion control. The echo cancellation filter uses an exponentially weighted step-size projection algorithm and has a
foreground/background structure. Noise and echo reduction, which is based on short-time spectral amplitude estimation,
reduce the level of ambient noise and the amount of residual echo hidden in that noise. Evaluation of this terminal shows that
the echo level is suppressed by 40 dB or more and the noise level is reduced by about 14 dB, levels that are good enough for
an audio teleconference in noisy office.