Texas Instruments Corporation

Georgia Tech Research Corporation

Takahiro Unno

Alan V McCree

Muhammad Zubair Ikram

Nitish Krishna Murthy

Sebastien Guiriec

Kwan Kin Truong

Baboo V Gowreesunker

Edwin Randolph Cole

Devangi Nikunj Parikh

Fabien Ober

Ali Erdem Ertan

Thierry Le Gall

Jesper Gormsen Kragh

Thierry LeGall

Thomas P Barnwell, Iii

A method of environmental noise compensation a speech audio signal is provided that includes estimating a fast audio energy level and a slow audio energy level in an audio environment, wherein the speech audio signal is not part of the audio environment, and applying a gain to the speech audio signal to generate an environment compensated speech audio signal, wherein the gain is updated based on the estimated slow audio energy level when the estimated fast audio energy level is not indicative of an audio event in the audio environment and the estimated gain is not updated when the estimated fast audio energy level is indicative an audio event in the audio environment.

Method and apparatus for environmental noise compensation by determining a presence or an absence of an audio event

At least one signal is received that represents speech and noise. In response to the at least one signal, frequency bands are generated of an output channel that represents the speech while attenuating at least some of the noise from the at least one signal. Within a kth frequency band of the at least one signal: a first ratio is determined of a clean version of the speech for a preceding time frame to the noise for the preceding time frame; and a second ratio is determined of a noisy version of the speech for the time frame n to the noise for the time frame n. In response to the first and second ratios, a gain is determined for the kth frequency band of the output channel for the time frame n.

Method, system and computer program product for attenuating noise in multiple time frames

In response to a signal failing to exceed an estimated level of noise by more than a predetermined amount for more than a predetermined continuous duration, the estimated level of noise is adjusted according to a first time constant in response to the signal rising and a second time constant in response to the signal falling, so that the estimated level of noise falls more quickly than it rises. In response to the signal exceeding the estimated level of noise by more than the predetermined amount for more than the predetermined continuous duration, a speed of adjusting the estimated level of noise is accelerated.

Method, system and computer program product for estimating a level of noise

In response to a first envelope within a kth frequency band of a first channel, a speech level within the kth frequency band of the first channel is estimated. In response to a second envelope within the kth frequency band of a second channel, a noise level within the kth frequency band of the second channel is estimated. A noise suppression gain for a time frame n is computed in response to the estimated speech level for a preceding time frame, the estimated noise level for the preceding time frame, the estimated speech level for the time frame n, and the estimated noise level for the time frame n. An output channel is generated in response to multiplying the noise suppression gain for the time frame n and the first channel.

Method, system and computer program product for suppressing noise using multiple signals

Acoustic echo control for hands-free phone has acoustic echo cancellation and echo suppression with a voice activity detection for the echo suppression based on near-end input power together with an estimate for acoustic echo cancellation gain.

Voice activity detector and method

A method and apparatus for cross-talk resistant adaptive noise cancellation. The method includes retrieving, via the processor, a primary signal and a reference signal, filtering the primary signal utilizing a filter H(z) and estimating a cross-talk, filtering the reference signal utilizing a filter H(z) and estimating the noise leakage of the reference signal, determining the difference between the noise leakage estimate from the primary signal and estimating a first post-filtering, determining the difference between the cross-talk estimate and the reference signal and estimating a second post-filtering, determining if the voice activity is detected in the primary signal, adapting filters Hand Hby de-correlation if the voice activity is detected, and adapting filter Hby NLMS if the voice activity is not detected, limiting maximum filter change during different conditions for protecting filters Hand Hfrom diverging, maintaining filter stability by tracking absolute sum of the coefficients of the convolution of Hand H, obtaining a primary output and a reference output utilizing the first post-filtering and the second post-filtering, and utilizing the primary output and the reference output for cross-talk resistant adaptive noise cancellation.

Method and apparatus for cross-talk resistant adaptive noise canceller

Hands-free phones with echo cancellation using dual filters, one fast adapting filter and one slow adapting filter; the choice of filters includes switching with hysteresis from recent performance, and the fast adapting filter has step size control to limit relative filter update energy and the slow adapting filter limits filter divergence.

Method and apparatus for acoustic echo cancellation utilizing dual filters

Hands-free phones with voice activity detection using a comparison of frame power estimate with an adaptive frame noise power estimate, automatic gain control with fast adaptation and minimal speech distortion, echo cancellation updated in the frequency domain with stepsize optimization and smoothed spectral whitening, and echo suppression with adaptive talking-state transitions.

Echo suppression with increment/decrement, quick, and time-delay counter updating

Layered code-excited linear prediction (CELP) speech encoders have progressively weaker perceptual weighting filters for each of the successive enhancement layers and decoders have progressively weaker short-term postfilters for increased bit rates (increased number of enhancement layers decoded) and a long-term postfilter for all bit rates.

Layered celp system and method with varying perceptual filter or short-term postfilter strengths

A decoder for code excited LP encoded frames with both adaptive and fixed codebooks; erased frame concealment uses repetitive excitation plus a smoothing of pitch gain in the next good frame, plus multilevel voicing classification with multiple thresholds of correlations determining linear interpolated adaptive and fixed codebook excitation contributions.

Concealment of frame erasures and method

A decoder for code excited LP encoded frames with both adaptive and fixed codebooks; erased frame concealment uses muted repetitive excitation, threshold-adapted bandwidth expanded repetitive synthesis filter, and jittered repetitive pitch lag.

A system and method for enhancing the speech quality of the mixed excitation linear predictive (MELP) coder and other low bit-rate speech coders. The system and method employ a plosive analysis/synthesis method, which detects the frame containing a plosive signal, applies a simple model to synthesize the plosive signal, and adds the synthesized plosive to the coded speech. The system and method remains compatible with the existing MELP coder bit stream.

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Richardson, TX, United States of America

Takahiro Unno