Nonlinear Acoustic Echo Cancellation for Mobile Phones

Acoustic echo cancelation (AEC) composes afundamental property of speech processing to enable a pleasanttelecommunication conversation. Without this property of thetelephone the communicator would hear an annoying echo of hisown voice along with the speech from the other communicator.This would make a conversation through any telecommunicationdevice an unpleasant experience.With the advent of low cost hands free communication devicesthe issue of nonlinear echo became prominent because thesedevices use cheap loudspeakers that produce annoying sound inaddition to the desired sound which will cause nonlinear echothat cannot be cancelled by linear echo cancellers.In this paper a Harmonic Distortion Residual Echo Cancelationalgorithm has been chosen for further investigations (HDRES).The results show that it may be possible to use an adaptive filter,which has both low complexity and fast convergence, in anoperating AEC system. However, the request for such a system towork would be that a doubletalk detector is implemented alongwith the adaptive algorithm. That way the doubletalk situationcould be found and the adaptation of the algorithm could bestopped. Thus, the major part of the speech would be saved.

Keywords:

Harmonic distortion residual echo suppressor (HDRES) , Acoustic echo cancelation (AEC) , nonlinear echo , Adaptive filter , Kernels Scheme , Modulated Complex Lapped Transform (MCLT)