Feature extraction method for a speech signal
First Claim
1. A method for extracting features from a speech signal comprising the steps of:
- determining spectral energies (x1, . . . , xN) of a speech signal by brief duration spectral analysis;
obtaining logarithmized spectral energies (y1, . . . , yn) from said spectral energies (x1, . . . xN); and
space="preserve" listing-type="equation">y.sub.i (n)=y.sub.i '"'"'(n) -y.sub.i +(n) with i=1, . . . , Kforming channel-compensated spectral energies (y1, . . . yN) from individual spectral energies yi (n) using a high-pass filter with time-dependent filter coefficients, wherein ##EQU8## wherein yi0, α
i0 and β
0 and are constants that are acquired from statistical examinations of the speech signal, andn(n) is a function monotonously rising with n.
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Abstract
The invention expands a feature extraction unit of a type known in the art with an adaptive channel compensation. The filter coefficients for a high-pass filter for eliminating the chronologically sliding average are set time-dependently with the adaptive channel compensation. As a result, a faster channel adaptation, and a better error compensation in the speech feature extraction are achieved, leading to a more reliable speech recognition. The parameters for the individual function blocks of the feature extraction unit are determined and stored in advance for specific speech transmission channels such as in mobile radio telephone, ISDN and analog speech transmission. The speech recognition with the assistance of the feature extraction unit can subsequently then ensue in channel-associated fashion with the stored parameters values.
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Citations
9 Claims
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1. A method for extracting features from a speech signal comprising the steps of:
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determining spectral energies (x1, . . . , xN) of a speech signal by brief duration spectral analysis; obtaining logarithmized spectral energies (y1, . . . , yn) from said spectral energies (x1, . . . xN); and
space="preserve" listing-type="equation">y.sub.i (n)=y.sub.i '"'"'(n) -y.sub.i +(n) with i=1, . . . , Kforming channel-compensated spectral energies (y1, . . . yN) from individual spectral energies yi (n) using a high-pass filter with time-dependent filter coefficients, wherein ##EQU8## wherein yi0, α
i0 and β
0 and are constants that are acquired from statistical examinations of the speech signal, andn(n) is a function monotonously rising with n. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification