Selective shaping of communication signals

• US 20050249361A1
• Filed: 05/05/2005
• Published: 11/10/2005
• Est. Priority Date: 05/05/2004
• Status: Active Grant

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Deka Products Limited Partnership
• Inventors: Beavis, Russell H., Kane, Derek G.
• Granted Patent: US 8,275,147 B2
• Time in Patent Office: Days
• US Class Current: 381/92
• CPC Class Codes: G01S 3/8006 Multi-channel systems specially adapted for direction-finding, i.e. having a single aerial system capable of giving simultaneous indications of the directions of different signals
• CPC Class Codes: G01S 3/8083 determining direction of source
• CPC Class Codes: G10K 11/346 using phase variation
• CPC Class Codes: G10L 2021/02165 Two microphones, one receiving mainly the noise signal and the other one mainly the speech signal
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: H04R 2201/401 2D or 3D arrays of transducers
• CPC Class Codes: H04R 2201/403 Linear arrays of transducers
• CPC Class Codes: H04R 2410/01 Noise reduction using microphones having different directional characteristics
• CPC Class Codes: H04R 25/407 Circuits for combining signals of a plurality of transducers
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

Angular discrimination between signals is described. Multiple signals are sampled with multiple signal sensors spatially separated from each other. Respective transform signals are determined that are representative of each sampled signal. If a difference between the transform signals in a given transform kernel bin is greater than a difference threshold, a first transform signal is modified by altering that kernel bin. Then the resulting modified transform signal is inverse transformed.

Claims

1. A method of angular discrimination between signals, the method comprising:

sampling a plurality of signals with a plurality of signal sensors spatially separated from each other;

determining respective transform signals representative of each sampled signal;

if a difference between the transform signals in a given transform kernel bin is greater than a difference threshold, modifying a first transform signal by altering that kernel bin; and

inverse transforming the modified transform signal.

2. A method according to claim 1, wherein the inverse transformed signal is output to a user.

3. A method according to claim 1, wherein reducing transform kernel bins is based on use of a comb filter function.

4. A method according to claim 1, wherein the first transform signal is modified by reducing that transform kernel bin to zero.

5. A method according to claim 1, wherein the transform signals are Fourier transforms of the signals.

6. A method according to claim 1, wherein there are two signals.

7. A method according to claim 1, wherein there are two signal sensors.

8. A method according to claim 1, wherein the signals are audio signals.

9. A method according to claim 1, wherein the signals are radio signals.

10. An audio system adapted to the use the method according to any of claims 1-9.

11. An audio system according to claim 10, wherein the system is part of an assisted listening device.

12. An audio system according to claim 10, wherein the system is part of a wireless telephone, a speaker phone, a speaker podium, or a boom microphone.

13. A method for suppressing off-axis noise in a sound-capture system for providing sound to a subject, the method comprising:

collecting sound data from at least two spatially separated microphones;

transforming the collected sound data for each microphone to obtain a spectrum over values of frequency of the sound data for each microphone;

creating a comb of weights for each value of frequency, the weight being determined based upon a criterion applied to the phase angle associated with that frequency value;

obtaining a vector product of the comb of weights with the spectrum of a specified microphone of the at least two spatially separated microphones to form an output signal spectrum;

performing an inverse transform of the output signal spectrum to obtain an output signal;

broadcasting the output signal to the subject.

14. A method according to claim 13, wherein collecting sound data includes storing the sound data over the course of a collection period in a memory buffer.

15. A method according to claim 13, wherein transforming the collected sound data for each microphone includes performing a Fourier transform of the collected sound data.

16. A method according to claim 13, wherein creating a comb of weights includes defining a weight for each value of frequency wherein the weight depends upon a relative phase of the value at that frequency of the phase of a first microphone relative to the value of the phase of a second microphone.

17. A method according to claim 13, wherein creating a comb of weights allows for specification of a band of angles about a non-zero value of angle of incidence within which to accept signals.

18. An audio system adapted to the use the method according to any of claims 13-17.

19. An audio system according to claim 18, wherein the system is part of an assisted listening device.

20. An audio system according to claim 18, wherein the system is part of a wireless telephone, a speaker phone, a speaker podium, or a boom microphone.