Patent ID: 7565286
Filing Date: 2009-07-21
Classification: G01N,G10L,H01Q

Abstract:
1. A method for recovering lost or unreliable speech samples in a speech transmission system, comprising the steps of: (a) receiving a composite sequence of speech samples which includes a sequence of unreliable speech samples and a sequence of reliable speech samples, each speech sample having a value and a position in the composite speech sequence, the composite sequence of speech samples having a pitch period T (b) identifying a set of time lags from correlations between at least some of the reliable speech samples; (c) for a speech sample from a first subset of speech samples from the composite sequence of speech samples, the first subset of speech samples including unreliable speech samples from the sequence of unreliable speech samples, selecting a set of reliable speech samples wherein each reliable speech sample is offset from the speech sample by a time lag from the set of time lags; (d) computing a periodic estimate for the speech sample from the first subset of speech samples using the set of reliable speech samples and using an adaptive FIR interpolation filter, wherein the adaptive FIR interpolation filter is dependent on a position of the speech sample from the first subset of speech samples; (e) repeating steps (c) and (d) for each speech sample from the first subset of speech samples so as to obtain periodic estimates for the unreliable speech samples; (f) producing a recovered sequence of speech samples utilizing the periodic estimates for each unreliable speech sample; wherein step (c) comprises selecting the set of reliable speech samples to include speech samples from a first sequence of reliable speech samples preceding the sequence of unreliable speech samples, and a second sequence of reliable speech samples following the sequence of unreliable speech samples, so that step (d) comprises computing the periodic estimate for the speech sample based on at least one reliable speech sample preceding said speech sample and at least one reliable speech sample following said speech sample; wherein the FIR interpolation filter has tap coefficients determined from correlations between at least some of the reliable speech symbols; wherein the step of identifying the set of time lags between T