Patent US4158749A successfully refreshed from Google Patents.
US4158749A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for discriminating speech signals from noise
Assignee: Thales SA
•
Filing: 1978-02-06
•
Granted: 1979-06-19
•
Expires: 1998-02-06
Abstract
Abstract An audio squelch circuit uses spectral analysis of the audio signal to derive two test signals, one of the two indicating speech presence "energy" and the other "voiced" speech presence. The two test signals are logic-AND combined to decide speech presence and open the squelch gate. Detection of speech in the audio signal, composed of a voiced segment which is both preceded and followed by a non-voiced (consonant) segment, is improved by correspondingly lengthening the "voiced" test signal pulse with both earlier (anticipatory) initiation by a time interval "D," and with a later (prolonged) completion by a time interval "d".
Inventors
- 👤 Pierre Deman
- 👤 Jean Potage
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:59
CPC Classifications
G; G10; G10L; G10L25/00; G10L25/78
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
286 words
An arrangement for discriminating speech signals from noise in an input signal, said arrangement comprising: a delay line for imparting to said input signal a delay of duration D, said delay line having at least one output; first means for generating a first test signal, indicative, with a limited degree of probability, of the presence of speech signals, voiced or unvoiced, in the signal appearing at said output of said delay line; second means, having an input for receiving said input signal, for generating a second test signal indicative, with a higher degree of probability, with a delay due to the response time of said second means, of the presence of voiced sound speech signals, in said input signal; third means for prolonging said second test signal by a duration d; and further means for delivering a speech decision signal, relative to the signal appearing at said output of said delay line, in the presence of both said first test signal and the prolonged second test signal; said duration D and d being taken sufficiently high for the duration of the prolonged second test signal to encompass on both sides the time interval during which the signals in response to which the second test signal was generated appear at said output of said delay line, the time elapsing between the beginning of the prolonged second test signal and the beginning of said time interval having a duration sufficient for the auditive identification of an unvoiced consonant preceding a voiced sound, and the time elapsing between the end of said time interval and the end of said prolonged second test signal having a duration sufficient for the auditive identification of an unvoiced consonant following a voiced sound.
Claim 2
Dependent Claim
286 words
An arrangement for discriminating speech signals from noise in an input signal, said arrangement comprising: a delay line for imparting to said input signal a delay of duration D, said delay line having at least one output; first means for generating a first test signal, indicative, with a limited degree of probability, of the presence of speech signals, voiced or unvoiced, in the signal appearing at said output of said delay line; second means, having an input for receiving said input signal, for generating a second test signal indicative, with a higher degree of probability, with a delay due to the response time of said second means, of the presence of voiced sound speech signals, in said input signal; third means for prolonging said second test signal by a duration d; and further means for delivering a speech decision signal, relative to the signal appearing at said output of said delay line, in the presence of both said first test signal and the prolonged second test signal; said duration D and d being taken sufficiently high for the duration of the prolonged second test signal to encompass on both sides the time interval during which the signals in response to which the second test signal was generated appear at said output of said delay line, the time elapsing between the beginning of the prolonged second test signal and the beginning of said time interval having a duration sufficient for the auditive identification of an unvoiced consonant preceding a voiced sound, and the time elapsing between the end of said time interval and the end of said prolonged second test signal having a duration sufficient for the auditive identification of an unvoiced consonant following a voiced sound.
Claim 3
Dependent Claim
25 words
A discriminating arrangement as claimed in claim 1, including logic means wherein each test signal is represented by a logic level of a logic signal.
Claim 4
Dependent Claim
180 words
A discriminating arrangement as claimed in claim 2, wherein said logic means process test signals including U being an elementary test signal corresponding to level 1 of a logic signal u(t), and denoting an energy imbalance above a threshold value between two acoustic frequency bands, M and M' being two elementary test signals respectively corresponding to level 1 of two logic signals m(t) and m'(t), and denoting, respectively in two acoustic frequency bands, the presence of a modulating frequency in a frequency band including the vibration frequencies of the vocal cords, Z and Z' being two elementary test signals respectively corresponding to level 1 of two logic signals z(t) and z'(t), and representing a density below a threshold value of the passages to zero respectively in the input signal and in the differentiated input signal, and B an elementary test signal corresponding to level 1 of a logic signal b(t), and denoting an energy above a threshold value in at least one acoustic frequency band, the second test signal V is level 1 of a logic signal v(t) with v(t)=u(t)·[m(t)+m'(t)]+b(t)·z(t)·z'(t).
Claim 5
Dependent Claim
26 words
A discriminating arrangement as claimed in claim 3, wherein the first test signal is level 1 of the signal obtained by means delaying the signal b(t).
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-06-18 | 1982-12-18 | 1983-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-06-18 | 1986-12-18 | 1987-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-06-18 | 1990-12-18 | 1991-06-19 | $7700.00 | Window Closed / Lapsed |