Abstract: A method is provided which is suitable to cope with non-linear echo paths during acoustic echo cancellation in speakerphones. Non-linear paths occur particularly in hands-free operation of, e.g., a mobile phone, due to driving the amplifier and loudspeaker in the non-linear range. The idea is to combine the commonly known one microphone approach of linear acoustic echo cancellation using an adaptive filter and a post-processor together with a multiple microphone approach using beam forming which separately removes the non-linear part of the echo.

Abstract: An audio processing arrangement (200) comprises a plurality of audio sources (101, 102) generating input audio signals, a processing circuit (110) for deriving processed audio signals from the input audio signals, a combining circuit (120) for deriving a combined audio signal from the processed audio signals, and a control circuit (130) for controlling the processing circuit in order to maximize a power measure of the combined audio signal and for limiting a function of gains of the processed audio signals to a predetermined value. In accordance with the present invention, the audio processing arrangement (200) comprises a pre-processing circuit (140) for deriving pre-processed audio signals from the input audio signals to minimize a cross-correlation of interferences comprised in the input audio signals. The pre-processed signals are provided to the processing circuit (110) instead of the input audio signals.

Abstract: An acoustic echo cancellation device (1) for canceling an echo in a microphone signal (z) in response to a far-end signal (x) comprises: an adaptive filter unit (10) arranged for filtering the far-end signal (x) so as to produce an echo cancellation signal (y), —a combination unit (12) arranged for combining the echo cancellation signal (y) with the microphone signal (z) so as to produce a residual signal (r), and a post-processor unit (13) arranged for substantially removing any remaining echoes from the residual signal. In accordance with the invention, the device further comprises: —a near-end pitch estimation unit (18) arranged for estimating the pitch of any near-end signal (s) contained in the microphone signal (z) and for controlling the post-processor unit (13) in dependence of the estimated pitch such that harmonics of the estimated pitch may be substantially preserved.

Abstract: An audio processing arrangement (200) comprises a plurality of audio sources (101, 102) generating input audio signals, a processing circuit (110) for deriving processed audio signals from the input audio signals, a combining circuit (120) for deriving a combined audio signal from the processed audio signals, and a control circuit (130) for controlling the processing circuit in order to maximize a power measure of the combined audio signal and for limiting a function of gains of the processed audio signals to a predetermined value. In accordance with the present invention, the audio processing arrangement (200) comprises a pre-processing circuit (140) for deriving pre-processed audio signals from the input audio signals to minimize a cross-correlation of interferences comprised in the input audio signals. The pre-processed signals are provided to the processing circuit (110) instead of the input audio signals.

Abstract: A method is provided which is suitable to cope with non-linear echo paths during acoustic echo cancellation in speakerphones. Non-linear paths occur particularly in hands-free operation of, e.g., a mobile phone, due to driving the amplifier and loudspeaker in the non-linear range. The idea is to combine the commonly known one microphone approach of linear acoustic echo cancellation using an adaptive filter and a post-processor together with a multiple microphone approach using beam forming which separately removes the non-linear part of the echo.

Abstract: A system (1) is described which is suited for suppressing audio distortion. The system comprises echo cancelling means (g1, g2) coupled between an audio output (4) and a distorted desired audio sensing microphone array (3), and a filter arrangement (7) coupled to the echo cancelling means (g1, g2) and/or the microphone array (3). The filter arrangement (7) includes filter coefficients representing at least a part of the audio distortion, such as reverberation. The system also comprises an at least partly mirrored circuit arrangement (g?, 7?) for copying thereby simulated audio distortion representative filter coefficient values into the filter coefficients of said filter arrangement (7). Such copied values can be then used for suppressing reverberation in a distorted desired signal by the filter arrangement (7).

Abstract: An audio enhancement system (1) for speech recognition or voice control is described, comprising a signal input for carrying a distorted desired signal (z), a reference signal input, and a spectral processor (SP) coupled to both signal inputs for processing the distorted desired signal (z) by means of a reference signal (x) acting as an estimate for the distortion of the desired signal. The spectral processor (SP) is equipped for said processing such that a factor C? is determined, whereby said estimate is a function of the factor C? times the spectral power of the reference signal (x), and the factor C is determined as the spectral ratio between those components of the signals z and x, which are essentially stationary with time. Such a factor determined by stationary parts of those signals makes application of a critical speech detector in the audio enhancement system superfluous.

Abstract: An acoustic echo cancellation device (1) for canceling an echo in a microphone signal (z) in response to a far-end signal (x) comprises: an adaptive filter unit (10) arranged for filtering the far-end signal (x) so as to produce an echo cancellation signal (y),—a combination unit (12) arranged for combining the echo cancellation signal (y) with the microphone signal (z) so as to produce a residual signal (r), and a post-processor unit (13) arranged for substantially removing any remaining echoes from the residual signal. In accordance with the invention, the device further comprises:—a near-end pitch estimation unit (18) arranged for estimating the pitch of any near-end signal (s) contained in the microphone signal (z) and for controlling the post-processor unit (13) in dependence of the estimated pitch such that harmonics of the estimated pitch may be substantially preserved.

Abstract: An audio signal processing device is described for deriving auxiliary audio signals, such as audio direction sensing signals or a center audio signal from first and second audio signals through first and second filter paths, each of which comprises a first adaptive filter, and a first summing means is provided for coupled to the first adaptive filters for providing a summed audio signal at its summing output. Each filter path further comprises a second adaptive filter coupled to said summing output, whose respective adaptive filter coefficients are transferred to the first adaptive filters and are adapted in response to respective comparisons of the first and second audio signals with filtered sums of the first and second audio signals. Therewith correlated and uncorrelated parts of the input audio signals are processed effectively.

Abstract: An audio signal processing device is described for deriving auxiliary audio signals, such as audio direction sensing signals or a center audio signal from first and second audio signals through first and second filter paths, each of which comprises a first adaptive filter, and a first summing means is provided for coupled to the first adaptive filters for providing a summed audio signal at its summing output. Each filter path further comprises a second adaptive filter coupled to said summing output, whose respective adaptive filter coefficients are transferred to the first adaptive filters and are adapted in response to respective comparisons of the first and second audio signals with filtered sums of the first and second audio signals. Therewith correlated and uncorrelated parts of the input audio signals are processed effectively.

Abstract: Audio reproduction systems are used to reproduce audio signals. A disadvantage of known audio reproduction systems is that in most cases with stereo or multichannel signals the quality performance of reproduction is very much dependent on the listening position.