Patent ID: 7809129

Claim:
An echo canceller, comprising: a noise environment classifier that detects a level of noise present on an uplink signal path and generates a noise classifier based on the level of noise; a double talk detector that: detects whether uplink audio is present on the uplink signal path; detects whether downlink audio is present on a downlink signal path; and generates a double talk flag based at least on the noise classifier, whether uplink audio is present on the uplink signal path and whether downlink audio is present on the downlink signal path; a first multi-band filter that receives a first input signal and generates a first plurality of sub-band signals, each of the first plurality of sub-band signals comprising a respective sub-band of the first input signal; a second multi-band filter that receives a second input signal and generates a second plurality of sub-band signals, each of the second plurality of sub-band signals comprising a respective sub-band of the second input signal; a plurality of adaptive filters, each of the adaptive filters receiving the double talk flag and a respective one of the second sub-band signals, and filtering the second sub-band signal in accordance with the double talk flag to generate a filtered second sub-band signal; a plurality of adders, each of the adders generating a respective third sub-band signal that is a difference of a respective one of the first sub-band signals and a respective one of the respective filtered second sub-band signals; and a non-linear filter that processes the double talk flag, the noise classifier and an uplink signal to generate an output signal having reduced echo.