US4454609A
Expired / Lapsed
US
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Speech intelligibility enhancement
Assignee: Sundstrand Corp
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Filing: 1981-10-05
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Granted: 1984-06-12
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Expires: 2001-10-05
Abstract
Abstract In a communications system, consonant high frequency sounds are enhanced: the greater the high frequency content relative to the low, the more such high frequency content is boosted.
Inventors
- 👤 James M. Kates
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:30
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
111 words
A system for processing an input speech signal comprising means responsive to said input speech signal for estimating the short-time spectral content of said input speech signal as a function of frequency relative to the short-time spectral content at a specified frequency or frequency region of said input speech signal: control means responsive to said spectral content estimate for determining when consonants are present in said input speech signal and for providing one or more control signals; and means responsive to said one or more control signals for dynamically modifying the short-time spectral content of said input speech signal to produce an output speech signal in which said consonants are enhanced.
Claim 2
Independent Claim
111 words
A system for processing an input speech signal comprising means responsive to said input speech signal for estimating the short-time spectral content of said input speech signal as a function of frequency relative to the short-time spectral content at a specified frequency or frequency region of said input speech signal: control means responsive to said spectral content estimate for determining when consonants are present in said input speech signal and for providing one or more control signals; and means responsive to said one or more control signals for dynamically modifying the short-time spectral content of said input speech signal to produce an output speech signal in which said consonants are enhanced.
Claim 3
Dependent Claim
39 words
A system in accordance with claim 1 wherein the estimating means estimates the short-time spectral content in each of a plurality of selected frequency bands relative to the short-time spectral content in one or more of said frequency bands.
Claim 4
Independent Claim
96 words
A system in accordance with claims 1 or 2 wherein said estimating means includes means for separating said input speech signal into a plurality of selected frequency bands; and means responsive to the portions of said input speech signal in each of said frequency bands for estimating the short-time spectral content in each of said frequency bands relative to the short-time spectral content in a selected one or more of said frequency bands; said control means being responsive to the short-time spectral content estimates in said frequency bands for producing said one or more control signals.
Claim 5
Dependent Claim
16 words
A system in accordance with claim 3 wherein said separating means is a band of filters.
Claim 6
Dependent Claim
52 words
A system in accordance with claim 3 wherein said estimating means includes a plurality of envelope detection means for detecting the envelope characteristics of said input speech signal in each of said frequency bands; and said control means is responsive to said envelope characteristics for providing said one or more control signals.
Claim 7
Dependent Claim
40 words
A system in accordance with claim 5 wherein said control means includes means responsive to said envelope characteristics for providing a plurality of weighting signals; and means responsive to said weighting signals for producing said one or more control signals.
Claim 8
Independent Claim
70 words
A system in accordance with claims 1, 2, 3, 4, 5 or 6 wherein said modifying means includes a plurality of filter circuits each having a different characteristic over the frequency spectrum of said input speech signal; and means responsive to said one or more control signals for selecting one of said plurality of filter circuits to modify said input speech signal so as to produce said output speech signal.
Claim 9
Independent Claim
64 words
A system in accordance with claims 2, 3, 4, 5 or 6 wherein said modifying means includes means 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 for combining the modified input speech signal in each of said selected frequency bands to produce said output speech signal.
Claim 10
Dependent Claim
38 words
A system in accordance with claim 8 wherein said modifying means 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
86 words
A system in accordance with claims 2, 3, 4, 5 or 6 wherein said modifying means includes a plurality of second filter means for separating said input speech signal into a plurality of second selected frequency bands; means 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 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
39 words
A system in accordance with claim 10 wherein said modifying means 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
48 words
A system in accordance with claim 6 wherein said weighting signal producing means includes matrix means responsive to said envelope characteristics for multiplying said envelope characteristics by a plurality of second coefficient values; and means for combining said multiplied envelope characteristics so as to produce said weighting signals.
Claim 14
Dependent Claim
71 words
A system in accordance with claim 12 wherein said combining means 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
43 words
A system in accordance with claim 9 wherein 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
18 words
A system in accordance with claim 14 wherein said first selected gains are unity below said selected levels.
Claim 17
Dependent Claim
34 words
A system in accordance with claim 15 wherein 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
25 words
A system in accordance with claim 16 where N is selected as equal to a value within a range from about 1 to about 3.
Claim 19
Dependent Claim
15 words
A system in accordance with claim 17 wherein N is selected as equal to 2.
Claim 20
Dependent Claim
32 words
A system in accordance with claim 5 wherein said envelope detection means detects the peaks of said envelope characteristics and the valleys of said envelope characteristics in each of said frequency bands.
Claim 21
Dependent Claim
43 words
A system in accordance with claim 19 and further including means 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
90 words
A method for processing an input speech signal comprising the steps of estimating the short-time spectral content of said speech signal as a function of frequency relative to the short-time spectral content at a specified frequency or frequency region of said input speech signal determining when consonants are present in said input signal in accordance with said short-time spectral content estimate; and dynamically modifying the short-time spectral content of said input speech signal in accordance with said determination to produce an output speech signal in which said consonants are enhanced.
Claim 23
Independent Claim
90 words
A method for processing an input speech signal comprising the steps of estimating the short-time spectral content of said speech signal as a function of frequency relative to the short-time spectral content at a specified frequency or frequency region of said input speech signal determining when consonants are present in said input signal in accordance with said short-time spectral content estimate; and dynamically modifying the short-time spectral content of said input speech signal in accordance with said determination to produce an output speech signal in which said consonants are enhanced.
Claim 24
Dependent Claim
47 words
A method in accordance with claim 21 wherein said dynamic modification includes the steps of producing one or more control signals in accordance with said determination; and controlling the dynamic modification of the short-time spectral content of said input speech signal in accordance with said control signals.
Claim 25
Independent Claim
51 words
A method in accordance with claims 21 or 22 wherein said estimating step includes the steps of estimating the short-time spectral contents of each of a plurality of first separate frequency bands of said input speech signal relative to the short-time spectral content of one or more of said frequency bands.
Claim 26
Dependent Claim
30 words
A method in accordance with claim 23 wherein 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 wherein said dynamic modification step includes the step of dynamically modifying the short-time spectral content of said input speech signal in a plurality of second separate frequency bands in accordance with said estimate.
Claim 28
Dependent Claim
25 words
A method in accordance with claim 25 wherein the plurality of first separate frequency bands substantially coincides with the plurality of second separate frequency bands.
Claim 29
Dependent Claim
25 words
A method in accordance with claim 25 wherein the plurality of first separate frequency bands are different from the plurality of second separate frequency bands.
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USPTO Annuity & Maintenance Windows
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| 3.5 Years (Year 4) | 1987-06-12 | 1987-12-12 | 1988-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-12 | 1991-12-12 | 1992-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-12 | 1995-12-12 | 1996-06-12 | $7700.00 | Window Closed / Lapsed |