Nokia Corporation

Gerald Enzner

Ville Mikael Myllyla

Jukka Vartiainen

Jari Petteri Sjoberg

Ville Myllylä

Sarmad Malik

Both a cascade and a multichannel joint Bayesian estimator are provided for suppressing acoustic echo. An expansion basis (Power/Fourier series) is selected to convert a sample-based input signal xinto a DFT-domain multichannel signal [X, . . . X]. The posterior of unknown states (e.g., mean &#x174;and covariance Pof the echo path Wand the mean &#xe2;and covariance Qof the nonlinear coefficients a; or channel-wise mean &#x174;and multichannel covarianceof a compound quantity formed by merging together the echo path Wand the inonlinear coefficient a) and model parameters &#x3b8;are estimated; and Kalman gain factor(s) Kare computed for optimal adaptation of the posterior of unknown states. An echo signal &#x176;is estimated using the multichannel input signal [X, . . . X] and the adapted posterior; and an error signal Eis generated. Residual echo is suppressed by post-filtering the error signal Ewith a weighting function &#x3c8;which depends on the adapted posterior, and the filtered error signal &#x15d;'is then transmitted to a far-end.

Recursive Bayesian controllers for non-linear acoustic echo cancellation and suppression systems

This invention describes a statistical adaptive-filter controller for digital acoustic echo control in hands-free telephones for achieving more consistent echo cancellation results (i.e. higher output signal quality) and simpler realizations of AEC units. The improvement using the simple statistical adaptive-filter controller is accomplished by optimizing a joint control of an echo canceller and a postfilter.

Statistical adaptive-filter controller

This invention discloses an improvement to a digital Acoustic Echo Control (AEC) in hands-free telephones. It describes an additional adaptive filter referred to as a residual echo filter, which is placed after the usual echo canceller and it is used to efficiently and accurately estimate a residual echo signal b(i) and a system coupling factor &#x3b2;(i), which can be utilized to establish an efficient control for the AEC system and construct the appropriate filters. The invention also describes a control block means performing a joint operation control of the echo canceller, residual echo suppressor and residual echo filter for achieving more consistent echo cancellation results and enhancing output signal quality.

Growing community of inventors

Neuhof/Zenn, Germany

Gerald Enzner