EP0076687A1
Expired / Lapsed
EP
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Speech intelligibility enhancement system and method
Assignee: SIGNATRON Inc
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Filing: 1982-10-04
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Granted: —
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Expires: 2002-10-04
Abstract
Abstract To enhance the intelligibility of speech, the consonant sounds are intensified and, in effect, their intensity equalised to that of the vowel sounds in a speech waveform. A short-time estimate of the relative spectral shape of an input speech signal is determined by envelope detectors (24) operating on the outputs of band pass filters (20). Control means are provided to respond to such relative spectral shape estimate by dynamically controlling a modification of the spectral shape of the actual speech signal so as to produce a modified output speech signal, the control means comprising a combination matrix (28) operating on the outputs of the envelope detectors (24) with a matrix of coefficients and producing weighted signals (29) as control signals. The control signals (29) act on gain selecting logic (30) to determine the gains of multipliers (31) through which respective different portions of the frequency spectrum of the input speech are coupled to a summation circuit (32) producing the consonant - enhanced output speech signal, the respective different portions of the frequency spectrum of the input speech being produced by a bank of filters (20) supplying the envelope detectors (24) or by a set of different filters (26).
Inventors
- 👤 James M. Kates
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 20:54
CPC Classifications
G; G10; G10L; G10L21/00; G10L21/02; G10L21/0316; G10L21/0364; G10L21/0208; G10L21/0216; G10L21/0232; H; H04; H04R; H04R2225/00; H04R2225/43
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
77 words
A system for processing an input speech signal, characterised by means (10) responsive to said input speech signal for estimating the short-time spectral shape of said input speech signal as a function of time; control means (11) responsive to said shape estimate for providing one or more control signals; and means (12) responsive to said one or more control signals for dynamically modifying the spectral shape of said input speech signal to produce an output speech signal.
Claim 2
Independent Claim
77 words
A system for processing an input speech signal, characterised by means (10) responsive to said input speech signal for estimating the short-time spectral shape of said input speech signal as a function of time; control means (11) responsive to said shape estimate for providing one or more control signals; and means (12) responsive to said one or more control signals for dynamically modifying the spectral shape of said input speech signal to produce an output speech signal.
Claim 3
Dependent Claim
40 words
A system in accordance with claim 1, characterised in that the estimating means (10) estimates the spectral content in each of a plurality of selected frequency bands relative to the spectral content in one or more of said frequency bands.
Claim 4
Independent Claim
99 words
A system in accordance with claims 1 or 2, characterised in that said estimating means (10) includes means (20) for separating said input speech signal into a plurality of selected frequency bands; and means (21) responsive to the portions of said input speech signal in each of said frequency bands for estimating the spectral content in each of said frequency bands relative to the spectral content in a selected one or more of said frequency bands; said control means (23) being responsive to the spectral content estimates in said frequency bands for producing said one or more control signals.
Claim 5
Dependent Claim
19 words
A system in accordance with claim 3, characterised in -:hat said separating means is a bank of filters (20).
Claim 6
Dependent Claim
57 words
A system in accordance with claim 3, characterised in that said estimating means (21) includes a plurality of envelope detection means (24) for detecting the envelope characteristics of said input speech signal in each of said frequency bands; and said control means (22) is responsive to said envelope characteristics for providing said one or more control signals.
Claim 7
Dependent Claim
44 words
A system in accordance with claim 5, characterised in that said control means includes means (28,29) responsive to said envelope characteristics for providing a plurality of weighting signals; and means (22) responsive to said weighting signals for producing said one or more control signals.
Claim 8
Independent Claim
69 words
A system in accordance with any preceding claim,characterised in that said modifying means includes a plurality of filter circuits (25) each having a different characteristic over the frequency spectrum of said input speech signal; and means (22) responsive to said one or more control signals for selecting one of said plurality of filter circuits (25) to modify said input speech signal so as to produce said output speech signal.
Claim 9
Independent Claim
68 words
A system in accordance with any one of claims 2 to 6, characterised in that said modifying means includes means (26) responsive to a plurality of control signals for modifying the spectral content of the input speech signal in each of said selected frequency bands; and means (27) for combining the modified input speech signal in each of said selected frequency bands to produce said output speech signal.
Claim 10
Dependent Claim
41 words
A system in accordance with claim 8, characterised in that said modifying means (30,31) provides a plurality of selectable gains for multiplying the amplitude of the input speech signal by a selected gain factor in each of said selected frequency bands.
Claim 11
Independent Claim
90 words
A system in accordance with any one of claims 2 to 6,characterised in that said modifying means includes a plurality of second filter means (26) for separating said input speech signal into a plurality of second selected frequency bands; means (30,31) responsive to a plurality of control signals for modifying the spectral content of the input speech signal in each of said second selected frequency bands; and means (32) for combining the modified input speech signal in each of said second selected frequency bands to produce said output speech signal.
Claim 12
Dependent Claim
43 words
A system in accordance with claim 10, characterised in that said modifying means (26,30,31, 32) provides a plurality of selectable gains for multiplying the amplitude of the input speech signal by a selected gain factor in each of said second selected frequency bands.
Claim 13
Dependent Claim
52 words
A system in accordance with claim 6, characterised in that said weighting signal producing means includes matrix means (28) responsive to said envelope characteristics for multiplying said envelope characteristics by a plurality of second coefficient values; and means (29) for combining said multiplied envelope characteristics so as to produce said weighting signals.
Claim 14
Dependent Claim
75 words
A system in accordance with claim 12, characterised in that said combining means (Fig. 6) includes means for combining envelope characteristics multiplied by said first coefficients to produce a plurality of first combined signals; means for combining said envelope characteristics multiplied by said second coefficients to produce a plurality of second combined signals; means for determining a plurality of ratios of said plurality of first and second combined signals, said ratios representing said weighting signals.
Claim 15
Dependent Claim
45 words
A system in accordance with claim 9, characterised in that said gain factors are selected so as to provide first selected gains when said weighting signals are below selected levels and second selected gains when said weighting signals are at or above said selected levels.
Claim 16
Dependent Claim
19 words
A system in accordance with claim 14, characterised in that first selected gains are unity below said selected levels.
Claim 17
Dependent Claim
36 words
A system in accordance with claim 15, characterised in that said second selected gains are proportional to W N , where W is the weighting signal for a selected band and N is a selected exponent.
Claim 18
Dependent Claim
27 words
A system in accordance with claim 16, characterised in that N is selected as equal to a value within a range from about 1 to about 3.
Claim 19
Dependent Claim
17 words
A system in accordance with claim 17, characterised in that N is selected as equal to 2.
Claim 20
Dependent Claim
35 words
A system in accordance with claim 5, characterised in that said envelope detector means (24) detects the peaks of said envelope characteristics and the valleys of said envelope characteristics in each of said frequency bands.
Claim 21
Dependent Claim
44 words
A system in accordance with claim 19, characterised by including means (40) for subtracting said valley envelope characteristics from said peak envelope characteristics to form combined envelope characteristics in each said frequency band and said control means in response to said combined envelope characteristics.
Claim 22
Independent Claim
42 words
A method for processing an input speech signal, characterised by the steps of estimating the spectral shape of said speech signal; dynamically modifying the spectral shape of said input speech signal in accordance with said estimate to produce an output speech signal.
Claim 23
Independent Claim
42 words
A method for processing an input speech signal, characterised by the steps of estimating the spectral shape of said speech signal; dynamically modifying the spectral shape of said input speech signal in accordance with said estimate to produce an output speech signal.
Claim 24
Dependent Claim
49 words
A method in accordance with claim 21, characterised in that said dynamic modification includes the steps of producing one or more control signals which are functions of said estimate; and controlling the dynamic modification of the spectral shape of said input speech signal in accordance with said control signals.
Claim 25
Dependent Claim
47 words
A method in accordance with claim 22, characterised in that said estimating steps include the steps of estimating the spectral content of a plurality of first separate frequency bands of said input speech signal relative to the spectral content of one or more of said frequency bands.
Claim 26
Dependent Claim
32 words
A method in accordance with claim 23, characterised in that said dynamic modification step includes the step of selecting a filter means having a spectral response specified in accordance with said estimate.
Claim 27
Dependent Claim
40 words
A method in accordance with claim 23, characterised in that dynamic modification step includes the step of dynamically modifying the spectral shape of said input speech signal in a plurality of second separate frequency bands in accordance with said estimate.
Claim 28
Dependent Claim
27 words
A method in accordance with claim 25, characterised in that the plurality of first separate frequency bands substantially coincides with the plurality of second separate frequency bands.
Claim 29
Dependent Claim
23 words
A method in accordance with claim 25, characterised in that the first separate frequency bands are different from the second separate frequency bands.
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US2183248A
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GB1384233A
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FR2226092A5
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DE2739609A1
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FR2394865A1
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DE2844979A1
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