Abstract: A method of signal processing according to one embodiment includes calculating an envelope of a first signal that is based on a low-frequency portion of a speech signal, calculating an envelope of a second signal that is based on a high-frequency portion of the speech signal, and calculating a plurality of gain factor values according to a time-varying relation between the envelopes of the first and second signal. The method includes attenuating, based on a variation over time of a relation between the envelopes of the first and second signals, at least one of the plurality of gain factor values. In one example, the variation over time of a relation between the envelopes is indicated by at least one distance among the plurality of gain factor values.

Abstract: In one embodiment, a method of signal processing includes calculating an envelope of a first signal that is based on a low-frequency portion of a speech signal, calculating an envelope of a second signal that is based on a high-frequency portion of the speech signal, and calculating a first plurality of gain factor values according to a time-varying relation between the envelopes of the first and second signals. The method includes, based on the first plurality of gain factor values, calculating a plurality of smoothed gain factor values. In one example, each of the plurality of smoothed gain factor values is based on a weighted sum of at least one of the first plurality of gain factor values and at least one smoothed gain factor value. In another example, the sum is adaptively weighted based on at least one distance among the plurality of gain factor values.

Abstract: A wideband speech encoder according to one embodiment includes a narrowband encoder and a highband encoder. The narrowband encoder is configured to encode a narrowband portion of a wideband speech signal into a set of filter parameters and a corresponding encoded excitation signal. The highband encoder is configured to encode, according to a highband excitation signal, a highband portion of the wideband speech signal into a set of filter parameters. The highband encoder is configured to generate the highband excitation signal by applying a nonlinear function to a signal based on the encoded narrowband excitation signal to generate a spectrally extended signal.

Abstract: In a device configurable to encode speech performing an closed loop re-decision may comprise representing a speech signal by amplitude components and phase components for a current frame and a past frame. In a first closed loop stage, a first set of compressed components and a first set of uncompressed components for a current frame may be generated. A first set of features may be generated by comparing current and past frame amplitude and/or phase components. In a second closed loop stage, a second set of compressed components for the current frame may be generated by compressing the first set of compressed components and compressing the first set of uncompressed components. Generation of a second set of features may be based on the second set of compressed components from the current frame and a combination of amplitude and/or phase components from the past frame.

Abstract: In one embodiment, a method of generating a highband excitation signal includes generating a spectrally extended signal by extending the spectrum of a signal that is based on an encoded lowband excitation signal; and performing anti-sparseness filtering of a signal that is based on the encoded lowband excitation signal. In this method, the highband excitation signal is based on the spectrally extended signal, and the highband excitation signal is based on a result of the anti-sparseness filtering.

Abstract: In one embodiment, a method of generating a highband excitation signal includes harmonically extending the spectrum of a signal that is based on a lowband excitation signal; calculating a time-domain envelope of a signal that is based on the lowband excitation signal; and modulating a noise signal according to the time-domain envelope. The method also includes combining (A) a harmonically extended signal based on a result of the harmonically extending and (B) a modulated noise signal based on a result of the modulating. In this method, the highband excitation signal is based on a result of the combining.

Abstract: A wideband speech encoder according to one embodiment includes a lowband encoder and a highband encoder. The lowband encoder is configured to encode a lowband portion of a wideband speech signal as a set of filter parameters and an encoded excitation signal. The highband encoder is configured to calculate values for coding parameters that specify a spectral envelope and a temporal envelope of a highband portion of the wideband speech signal. The temporal envelope is based on a highband excitation signal that is derived from the encoded excitation signal. In one such example, the temporal envelope is based on a difference in levels between the highband portion and a synthesized highband signal, wherein the synthesized highband signal is generated according to the highband excitation signal and a set of highband filter parameters.

Abstract: In one embodiment, a method of signal processing including includes encoding a low-frequency portion of a speech signal into at least an encoded narrowband excitation signal and a plurality of narrowband filter parameters; and generating a highband excitation signal based on a narrowband excitation signal. The encoded narrowband excitation signal includes a time warping, and the method includes applying a time shift to a high-frequency portion of the speech signal based on the information related to the time warping. The method also includes encoding the time-shifted high-frequency portion of the speech signal into at least one (A) a plurality of highband filter parameters and (B) a plurality of high band gain factors.

Abstract: A speech converter in a speech processing system modifies various aspects of input speech. The speech converter receives a formants signal representing an input speech signal. The speech converter may also receive a formant scaling command or a user selection of one of multiple control signals, each specifying a manner of modifying one or more of the received signals (i.e., formants, voicing, pitch, gain). The speech converter modifies at least one of the formants, voicing, pitch, and/or gain signals as specified by the selected voice font.

Abstract: A wideband speech encoder according to one embodiment includes a lowband encoder and a highband encoder. The lowband encoder is configured to encode a lowband portion of a wideband speech signal as a set of filter parameters and an encoded excitation signal. The highband encoder is configured to calculate values for coding parameters that specify a spectral envelope and a temporal envelope of a highband portion of the wideband speech signal. The temporal envelope is based on a highband excitation signal that is derived from the encoded excitation signal. In one such example, the temporal envelope is based on a difference in levels between the highband portion and a synthesized highband signal, wherein the synthesized highband signal is generated according to the highband excitation signal and a set of highband filter parameters.