Patent ID: 8737633

Claim:
A noise cancellation system, for generating a noise cancellation signal to be added to a wanted signal to mitigate the effects of ambient noise, said system comprising: an input, for receiving an input signal representing ambient noise; a detector, for detecting a magnitude of said input signal; and a voice activity detector, for detecting voiceless periods when said input signal does not contain a signal representing a voice, wherein said detector is adapted to detect the magnitude of said input signal during said voiceless periods, and wherein the system is adapted to operate in a first mode when said detected magnitude of said input signal is above a threshold value, and a second mode when said detected magnitude of said input signal is below the threshold value, the first mode comprising: generating a noise cancellation signal with a first magnitude for at least partially cancelling the ambient noise, the noise cancellation signal with said first magnitude being added to the wanted signal; the second mode comprising: generating a noise cancellation signal with a second magnitude that is less than the first magnitude, the noise cancellation signal with said second magnitude being added to the wanted signal.