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EP0332890A2
Expired / Lapsed
EP
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Cancellation of noise from a noise-degraded voice signal
Assignee: International Business Machines Corp
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Filing: 1989-02-22
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Granted: —
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Expires: 2009-02-22
Abstract
Abstract The disclosure describes a method and system for cancelling noise from sources that are distributed over a region, whereby two sensors are located so that a first sensor will detect both voice signals and noise signals, and a second sensor will detect only the noise signals. The voice signals picked up at the second sensor are negligible, and the noise signals picked up at both sensors are correlated. The signals output from each sensor are connected to means to divide each respective signal into a predetermined number of frequencies, such as 15 for example. Thereafter, both signals are combined to cancel effectively the noise component from the signal output having both voice and noise to leave a voice signal that is substantially noise free.
Inventors
- 👤 Robert Wu-Lin Chang
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 15:49
CPC Classifications
G; G10; G10L; G10L21/00; G10L21/02; G10L21/0208; G10L21/0216; G10L2021/02161; G10L2021/02165
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
100 words
A noise cancellation system, comprising: two sensors (17, 18) to detect voice and noise frequencies, one of said sensors (17) being located to detect voice plus noise frequencies, and the other of said sensors (18) being located to detect principally noise frequencies; two groups (19, 20) of narrowband filters, one group of narrowband filters being connected to one of said sensors (17), and the other group of said two groups being connected to the other of said sensors (18); and means(22) to process outputs from said two groups of narrowband filters to cancel said noise frequencies leaving principally voice frequencies.
Claim 2
Dependent Claim
100 words
A noise cancellation system, comprising: two sensors (17, 18) to detect voice and noise frequencies, one of said sensors (17) being located to detect voice plus noise frequencies, and the other of said sensors (18) being located to detect principally noise frequencies; two groups (19, 20) of narrowband filters, one group of narrowband filters being connected to one of said sensors (17), and the other group of said two groups being connected to the other of said sensors (18); and means(22) to process outputs from said two groups of narrowband filters to cancel said noise frequencies leaving principally voice frequencies.
Claim 3
Dependent Claim
43 words
A noise cancellation system as defined in claim 1 including a plurality of adaptive filters (21), one adaptive filter being connected to each narrowband filter in said other group of narrowband filters, intermediate the narrowband filters and said means (22) to process outputs.
Claim 4
Dependent Claim
23 words
3 A noise cancellation system as defined in claim 1 including voice recognition means (23) connected to said means (22) to process outputs.
Claim 5
Dependent Claim
31 words
A noise cancellation system as defined in claim 1 wherein said means (22) to process outputs includes means (30) to combine outputs from each respective narrowband filter in said two groups.
Claim 6
Dependent Claim
47 words
A noise cancellation system as defined in claim 4 wherein said means (30) to combine outputs includes separate means connected to receive the output from one narrowband filter in said one group and the output from the corresponding narrowband filter in said other group of narrowband filters.
Claim 7
Dependent Claim
19 words
A noise cancellation system as defined in claim 5 wherein said means(30) to combine is a subtract circuit means.
Claim 8
Dependent Claim
20 words
A noise cancellation system as defined in claim 1 including voice recognition means(23) connected to said subtract circuit means (30).
Claim 9
Dependent Claim
30 words
A noise cancellation system as defined in claim 5 wherein said narrowband filters are adapted to divide the output of each respective sensor into the same number of individual frequencies.
Claim 10
Dependent Claim
25 words
A noise cancellation system as defined in claim 8 wherein said narrowband filters divide the output of each respective sensor into approximately fifteen individual frequencies.
Claim 11
Dependent Claim
32 words
A noise cancellation system as defined in claim 8 wherein said narrowband filters divide the output of each respective sensor into a frequency range of approximately 200 Hertz for each narrowband filter.
Claim 12
Dependent Claim
27 words
A noise cancellation system as defined in claim 8 wherein said narrowband filters divide the output of each respective sensor into approximately 10 to 25 equal frequencies.
Claim 13
Dependent Claim
58 words
A noise cancellation system as defined in claim 9 including a plurality of adaptive filters, one connected to receive an output from each of said narrowband filters in said other of said two groups, means including subtract circuit means to combine corresponding outputs from said two sensors, and voice recognition means connected to receive the combined corresponding outputs.
Claim 14
Independent Claim
105 words
A method for cancelling noise from a noise-degraded speech signal, comprising: detecting a noise-degraded speech signal by placing a first sensor (17) so that a speech component will be dominant over a noise component; locating a second sensor (18) to detect a signal that is predominately said noise component, and so that a difference in phase displacement between said noise component in said noise-degraded speech and said noise component detected by said second sensor is small; dividing each of said signals into a plurality of narrow band frequencies; and processing said divided narrow band frequencies to obtain a speech signal that is substantially noise free.
Claim 15
Independent Claim
105 words
A method for cancelling noise from a noise-degraded speech signal, comprising: detecting a noise-degraded speech signal by placing a first sensor (17) so that a speech component will be dominant over a noise component; locating a second sensor (18) to detect a signal that is predominately said noise component, and so that a difference in phase displacement between said noise component in said noise-degraded speech and said noise component detected by said second sensor is small; dividing each of said signals into a plurality of narrow band frequencies; and processing said divided narrow band frequencies to obtain a speech signal that is substantially noise free.
Claim 16
Dependent Claim
48 words
A method of cancelling noise from a noise-degraded speech signal as defined in claim 11 wherein the step of dividing each of said signals from the two sensors into a plurality of narrow band frequencies includes the step of dividing them into the same number for each sensor.
Claim 17
Dependent Claim
38 words
A method of cancelling noise from a noise-degraded speech signal as defined in claim 14 wherein the step of dividing said signals into a plurality of frequencies includes the step of dividing them into approximately 200 Hertz each.
References Cited (Backward Citations)
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