A configurable adaptive filter that is used for echo cancellation is
disclosed, which includes a method of detecting a voice or no-voice
signal. The presence of a voice or no-voice signal is determined by
calculating a histogram of signal amplitude value over a period of time.
If this histogram has more than a predefined number of samples that are
above a threshold then the signal is classified as no-voice or periodic
otherwise the signal is classified as a voice signal. A variable maximum
amplitude limit and lower amplitude thresholds are disclosed to detect a
voice or no-voice from the histogram signal faster than traditional
methods utilized in echo cancelers. A configurable hysteresis time is used
to ensure the signal register primarily contains voice signal when the
filter coefficients of the echo canceler are allowed to adapt.
