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US 7,065,485 B1Granted
Enhancing speech intelligibility using variable-rate time-scale modification
AssigneeAT&T Corp.
InventorsNicola R. Chong-White, Richard Vandervoort Cox
Life of this patent
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Abstract
The method and preprocessor enhances the intelligibility of narrowband speech without essentially lengthening the overall time duration of the signal. Both spectral enhancements and variable-rate time-scaling procedures are implemented to improve the salience of initial consonants, particularly the perceptually important formant transitions. Emphasis is transferred from the dominating vowel to the preceding consonant through adaptation of the phoneme timing structure. In a further embodiment, the technique is applied as a preprocessor to a speech coder.
Claims25
A method for enhancing speech intelligibility of a speech signal, comprising:
- performing syllable segmentation on a frame of the speech signal in order to detect a syllable;
- dynamically determining a scaling factor for a segment of speech in response to performing syllable segmentation on a frame of the speech signal in order to detect a syllable, wherein the segment is contained in the frame;
- applying the scaling factor to the segment in order to modify a time scaling to the segment;
- and
- blending the segment with an overlapping segment in order to essentially retain a frequency attribute of the speech signal that is processed, wherein:
- the syllable is a time-scale modification syllable (TSMS) comprising a consonant-vowel transition and a steady-state vowel, and
- dynamically determining a scaling factor for a segment of speech comprises:
- setting the scaling factor to a first value, wherein time expansion occurs during the consonant-vowel transition;
- and
- setting the scaling factor to a second value, wherein time compression occurs during the steady-state vowel.
7 more elements
A method for enhancing an intelligibility of a speech signal comprising:
- adaptive spectral enhancing the speech signal, wherein a distinctness of spectral peaks of the speech signal is increased;
- emphasizing higher frequencies of the speech signal, wherein an upward spread of masking of the speech signal is reduced;
- extracting a frame from the speech signal;
- calculating an energy contour and a spectral feature transition rate (SFTR) contour corresponding to the frame;
- performing syllable segmentation utilizing the energy contour and the SFTR contour in order to detect a time-scale modification syllable (TSMS);
- applying a scaling factor to a segment of speech, wherein the segment corresponds to a portion of the frame, comprising:
- setting the scaling factor to a first value when a consonant-vowel transition is detected within the TSMS, time expansion occurring during the consonant-vowel transition;
- setting the scaling factor to a second value when a steady-state vowel is detected with the TSMS, time compression occurring during the steady-state vowel;
- and
- setting the scaling value to a third value for other portions of the speech signal;
- determining an overlapping segment that is best-matched to the segment according to a cross-correlation and waveform similarity criterion;
- calculating a time delay associated with the segment;
- adjusting the scaling factor associated with a subsequent segment according to the calculated time delay;
- overlapping and adding the segment and the overlapping segment;
- and
- outputting a modified frame in response to processing all constituent segments of the frame.
13 more elements
A method for enhancing an intelligibility of a speech signal comprising:
- extracting a frame from the speech signal;
- calculating an energy contour and a spectral feature transition rate (SFTR) contour corresponding to the frame;
- performing syllable segmentation utilizing the energy contour and the SFTR contour in order to detect a time-scale modification syllable (TSMS);
- applying a scaling factor to a segment of speech, wherein the segment corresponds to a portion of the frame, comprising:
- setting the scaling factor to a first value when a consonant-vowel transition is detected within the TSMS, time expansion occurring during the consonant-vowel transition;
- setting the scaling factor to a second value when a steady-state vowel is detected with the TSMS, time compression occurring during the steady-state vowel;
- and
- setting the scaling value to a third value for other portions of the speech signal;
- determining an overlapping segment that is best-matched to the segment according to a cross-correlation and waveform similarity criterion;
- calculating a time delay associated with the segment;
- adjusting the scaling factor associated with a subsequent segment according to the calculated time delay;
- overlapping and adding the segment and the overlapping segment;
- and
- outputting a modified frame in response to processing all constituent segments of the frame.
11 more elements
A method for enhancing an intelligibility of a speech signal that is processed by a speech coder, comprising:
- extracting a frame from the speech signal;
- performing syllable segmentation in order to detect a time-scale modification syllable (TSMS);
- applying a scaling factor to a segment, wherein the frame comprises at least one segment, comprising:
- setting the scaling factor to a first value when a consonant-vowel transition within the TSMS is detected, time expansion occurring during the consonant-vowel transition;
- setting the scaling factor to a second value when a steady-state vowel within the TSMS is detected, time compression occurring during the steady-state vowel;
- and
- setting the scaling factor to a third value for other portions of the frame;
- estimating a pitch component of the frame;
- determining an overlapping segment that is best-matched to the segment according to a cross correlation and waveform similarity criterion, and to the speech component if the frame has a voiced characteristic;
- combining the segment with an adjacent segment, comprising:
- overlapping and adding the segment and the overlapping segment if a correlation between the segment and the overlapping segment is greater than a threshold;
- and
- essentially retaining the segment if the correlation between the segment and the overlapping segment is less than the threshold;
- and
- outputting a modified frame to the speech coder in response to processing all constituent segments of the frame.
12 more elements
A method comprising:
- performing syllable segmentation on a frame of the speech signal in order to detect a syllable;
- dynamically determining a scaling factor for a segment of speech in response to performing syllable segmentation on a frame of the speech signal in order to detect a syllable, wherein the segment is contained in the frame;
- applying the scaling factor to the segment in order to modify a time scaling to the segment;
- and
- blending the segment with an overlapping segment in order to essentially retain a frequency attribute of the speech signal that is processed, wherein:
- performing syllable segmentation on a frame of the speech signal in order to detect a syllable comprises detecting abrupt changes in frequency domain characteristics of the speech signal.
3 more elements
Dependencies are inferred from the claim text.