A combination of noise suppression using a Bark band modified Weiner
filter and linear noise reduction improves elimination of noise in a
telephone. A detector for detecting long, non-speech intervals is coupled
to the output of the noise suppresser and controls selection of noise
suppression or noise reduction. A gain smoothing filter has a long time
constant when noise reduction is used and provides a gradual transition
from one level of gain to another. Comfort noise is smoothly inserted by
updating the data for generating comfort noise only during detected long,
non-speech intervals.