Abstract: The present technology provides a robust noise suppression system which may concurrently reduce noise and echo components in an acoustic signal while limiting the level of speech distortion. An acoustic signal may be received and transformed to cochlear domain sub-band signals. Features such as pitch may be identified and tracked within the sub-band signals. Initial speech and noise models may be then be estimated at least in part from a probability analysis based on the tracked pitch sources. Speech and noise models may be resolved from the initial speech and noise models and noise reduction may be performed on the sub-band signals and an acoustic signal may be reconstructed from the noise-reduced sub-band signals.

Abstract: Corrupted portions of an audio signal are detected and repaired. An audio signal may be received from an audio input device. The audio signal may include numerous sequential frames. One or more corrupted frames included in the audio signal may be identified. A frame approximating an uncorrupted frame and corresponding to each corrupted frame may be constructed. Each corrupted frame may be replaced with a corresponding constructed frame to generate a repaired audio signal. The repaired audio signal may be outputted via an audio output device.

Abstract: A frequency-domain method for format conversion or reproduction of 2-channel or multi-channel audio signals such as recordings is described. The reproduction is based on spatial analysis of directional cues in the input audio signal and conversion of these cues into audio output signal cues for two or more channels in the frequency domain.

Abstract: A stereo audio signal is processed to determine primary and ambient components by transforming the signal into vectors corresponding to subband signals, and decomposing the left and right channel vectors into ambient and primary components by matrix and vector operations. Principal component analysis is used to determine a primary component unit vector, and ambience components are determined according to a correlation-based cross-fade or an orthogonal basis derivation.

Abstract: An audio signal is processed to derive primary and ambient components of the signal. The signal is first transformed to generate frequency-domain subband signals. Primary and ambient components are separated by comparing frequency subband content using a complex-valued similarity metric, wherein one of the primary and ambient components is determined to be the residual after the other is identified using the similarity metric.

Abstract: An array processing system improves the spatial selectivity by forming multiple steered beams and carrying out a spatial analysis of the acoustic scene. The analysis derives a time-frequency mask that, when applied to a reference look-direction beam (or other reference signal), enhances target sources and substantially improves rejection of interferers that are outside of the specified region.

Abstract: A method of ambience extraction includes analyzing an input signal to determine the time-dependent and frequency-dependent amount of ambience in the input signal, wherein the amount of ambience is determined based on a signal model and correlation quantities computed from the input signals and wherein the ambience is extracted using a multiplicative time-frequency mask. Another method of ambience extraction includes compensating a bias in the estimation of a short-term cross-correlation coefficient. In addition, systems having various modules for implementing the above methods are disclosed.

Abstract: A two-channel phase-amplitude stereo encoding and decoding scheme enabling flexible and spatially accurate interactive 3-D audio reproduction via standard audio-only two-channel transmission. The encoding scheme allows associating a 2-D or 3-D positional localization to each of a plurality of sound sources by use of frequency independent inter-channel phase and amplitude differences. The decoder is based on frequency-domain spatial analysis of 2-D or 3-D directional cues in a two-channel stereo signal and re-synthesis of these cues using any preferred spatialization technique, thereby allowing faithful reproduction of positional audio cues and reverberation or ambient cues over arbitrary multi-channel loudspeaker reproduction formats or over headphones, while preserving source separation despite the intermediate encoding over only two audio channels.

Abstract: An audio signal is processed by transforming the signal into a frequency domain representation having a plurality of frequency subbands. A decorrelated signal is derived from the frequency domain representation using a phase rotation.

Abstract: An audio signal is processed in the frequency domain to convert an input signal format to an output signal format. That is, a multichannel audio signal intended for playback over a predefined speaker layout can be formatted to achieve spatial reproduction over a different layout comprising a different number of speakers.

Abstract: A frequency domain method for phase-amplitude matrixed surround decoding of 2-channel stereo recordings and soundtracks, based on spatial analysis of 2-D or 3-D directional cues in the recording and re-synthesis of these cues for reproduction on any headphone or loudspeaker playback system.

Abstract: An audio signal is processed to determine primary and ambient components by transforming the signal into frequency-domain vectors, and decomposing the left and right channel vectors into ambient and primary components by orthogonal projection.

Abstract: Allpass arrays of arbitrary order are presented. The transducers in the arrays are configured with weights corresponding to the FIR approximation of an allpass filter such that a nearly uniform array response is provided.

Abstract: A frequency band of an audio input signal is analyzed to determine if a transient is present. When transients are detected, modifications are made to the intensity levels corresponding to the frequency band for a brief time period.

Abstract: A memory-efficient system converting a signal from a first transform domain to a second transform domain. The system includes a first mechanism that obtains an input signal expressed via a first transform-domain signal representation. A second mechanism expresses the input signal via a second transform-domain signal representation without intermediate time-domain conversion. In the specific embodiment, the input signal is a Modified Discrete Cosine Transform (MDCT) signal. The second transform-domain signal representation is a Discrete Fourier Transform (DFT) signal. The second mechanism further includes a third mechanism that combines effects of an inverse MDCT, a synthesis window function, and an analysis window function, and provides a first signal in response thereto. A fourth mechanism converts the MDCT signal to the DFT signal based on the first signal.

Abstract: A memory-efficient system converting a signal from a first transform domain to a second transform domain. The system includes a first mechanism that obtains an input signal expressed via a first transform-domain signal representation. A second mechanism expresses the input signal via a second transform-domain signal representation without intermediate time-domain conversion. In the specific embodiment, the input signal is a Modified Discrete Cosine Transform (MDCT) signal. The second transform-domain signal representation is a Discrete Fourier Transform (DFT) signal. The second mechanism further includes a third mechanism that combines effects of an inverse MDCT, a synthesis window function, and an analysis window function, and provides a first signal in response thereto. A fourth mechanism converts the MDCT signal to the DFT signal based on the first signal.

Abstract: An electret transducer array and fabrication technique are disclosed. The array comprises a foil having a layer of insulating material and a layer of metal in contact therewith. The layer of metal comprises one or more discrete areas of metal which define the active areas of one or more transducers in the array. Electrical leads are coupled to the discrete areas of metal. By means of these leads, electrical signals produced by each transducer in response to incident acoustic signals may be accessed. The areas of metal may be formed by selectively removing metal from the foil, or by selective metal deposition. The layer of insulating material is electrostatically charged. The electret transducer array further comprises a porous backplate of sintered metal. The backplate further comprises a rough surface in contact with the layer of insulating material. The backplate serves as a common electrode for transducers of the array.