US 7,257,535 B2Granted

Parametric speech codec for representing synthetic speech in the presence of background noise

AssigneeLucent Technologies Inc.

InventorsJoseph Gerard Aguilar, Juin-Hwey Chen, Wei Wang, Robert W. Zopf

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Abstract

A system and method are provided for processing audio and speech signals using a pitch and voicing dependent spectral estimation algorithm (voicing algorithm) to accurately represent voiced speech, unvoiced speech, and mixed speech in the presence of background noise, and background noise with a single model. The present invention also modifies the synthesis model based on an estimate of the current input signal to improve the perceptual quality of the speech and background noise under a variety of input conditions. The present invention also improves the voicing dependent spectral estimation algorithm robustness by introducing the use of a Multi-Layer Neural Network in the estimation process. The voicing dependent spectral estimation algorithm provides an accurate and robust estimate of the voicing probability under a variety of background noise conditions. This is essential to providing high quality intelligible speech in the presence of background noise.

Claims4

Dependent claims

A system for processing an encoded audio signal having a number of frames, the system comprising:

a decoder comprising:
means for unquantizing at least three of a pitch period, a voicing probability, a mid-frame pitch period, and a mid-frame voicing probability of the audio signal;
means for producing a spectral magnitude envelope and a minimum phase envelope;
means for generating at least one control parameter using a signal-to-noise ratio computed using a gain and the voicing probability of the audio signal;
means for analyzing the spectral magnitude envelope and the minimum phase envelope, wherein the spectral magnitude envelope and the minimum phase envelope are analyzed using the at least one control parameter and at least one of the unquantized pitch period, the unquantized voicing probability, the unquantized mid-frame pitch period, and the unquantized mid-frame voicing probability;
and
means for producing a synthetic speech signal corresponding to the input audio signal using the analysis of the spectral magnitude envelope and the minimum phase envelope.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/261,969Filed 28 Oct 2005 · division
Priority: 26 Jul 1999
Published: US 2006/0064301 A123 Mar 2006
Granted: 14 Aug 2007
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G10L 19/265
Pre-filtering or post-filtering: pre-filtering, e.g. high frequency emphasis prior to encoding
G10L 19/093
Determination or coding of the excitation function; Determination or coding of the long-term prediction parameters: using sinusoidal excitation models
G10L 21/0272
Speech enhancement, e.g. noise reduction or echo cancellation: voice signal separating
G10L 25/18
Characterised by the type of extracted parameters: the extracted parameters being spectral information of each sub-band

Family

Application60/145,591Us provisional application · filed 26 Jul 1999
Application09/625,960Parent of this division · filed 26 Jul 2000
US 2006/0064301 A1Pre-grant publication · published 23 Mar 2006
US 7,092,881 B1Related patent
US 7,257,535 B2This patent

From the US filing history. Foreign family members aren’t listed.