Method for vectorial noise-reduction in speech, and implementation device

• US 5,500,903 A
• Filed: 12/28/1993
• Issued: 03/19/1996
• Est. Priority Date: 12/30/1992
• Status: Expired due to Term

• Current Assignee: Sextant Avionique
• Original Assignee: Sextant Avionique
• Inventors: Gulli, Christian
• Primary Examiner(s): Rogers, Scott A.
• Assistant Examiner(s): Grant, II, Jerome
• Application Number:
  US08/174,420
• Time in Patent Office: 812 Days
• Field of Search: 381/71, 381/94, 381/68.4, 381/68.2, 381/92
• US Class Current: 381/92
• CPC Class Codes: G01S 3/805 using adjustment of real or effective orientation of directivity characteristics of a transducer or transducer system to give a desired condition of signal derived from that transducer or transducer system, e.g. to give a maximum or minimum signal
• CPC Class Codes: G01S 3/86 with means for eliminating undesired waves, e.g. disturbing noises
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

A sound pick-up operation is carried out by means of at least four microphones positioned in a plane before the speaker, linear combinations are formed by additions and subtractions of the signals from these microphones and certain of these combinations are used as noise-only sources to process them by an adaptive vector filter to produce an estimation of the noise that is subtracted from the noisy signal.

Claims

1. A method for vectorial noise-reduction for a source of sound signals that is substantially a point source, comprising the steps of:

vectorially picking up sound signals by means of at least four equally spaced out microphones positioned in a plane before the source of sound signals

forming linear combinations from the sound signals by additions and subtractions of the sound signals from said microphones;

wherein the sum of all the sound signals from the microphones represents the noisy signal each of the other linear combinations of sound signals comprises as many subtractions as additions of the sound signals and represent noise only signals;

processing the linear combinations of the sound signals from the microphones that have as many subtractions as additions with a vectorial adaptive filter to produce an estimate of the noise of the noisy signal; and

subtracting said estimate of the noise of the noisy signal from the noisy signal.

2. A method according claim 1, wherein the vectorial noise-reduction implements an LMS or RLS type of algorithm.

3. A method according to claim 1, wherein the microphones are arranged in two orthogonal and coplanar sets, the normal to the plane thus formed being pointed towards the source of the sound signals to be processed.

4. A method according to claim 3 wherein, each set of microphones forms first and second physical antennas having the same directional major lobe with two frequencies separated by an octave and further comprising the step of adding the signals from the first and second physical antennas to form a servocontrol signal and using the servocontrol signal to servocontrol the the physical antenna'"'"'s orientation in terms of elevation angle and bearing and plane in which the microphones are positioned in relation to the source of sound signals.

5. A method according to claim 1, wherein the signals of all the microphones are sampled synchronously.

6. A method according to any of the claims 4 or 5, wherein the orientation, in terms of elevation angle and relative bearing, of the plane in which the microphones are positioned in relation to the source of sound signals is determined by a super-resolving method.

7. A method according to claim 6, wherein the super-resolving method is chosen from among the CAPON, LAGUNAS, AR or MUSIC methods.

8. A method for vectorial noise-reduction in a source that is substantially a point source, comprising at least one set of at least eight equally spaced out microphones, each followed by an amplifier, a sampling device, the sampling devices being all synchronous and connected to a binary conversion matrix comprising serializing connections and inverters, a first one of these outputs corresponding to the serializing of all the inputs, each of these other outputs corresponding to a different combination of of serializing operations and input inversions, the first output of this combiner device being connected to the (+) input of a subtractor and the others being connected via an adaptive filter to the (-) input of the subtractor.

9. A device according to claim 8, comprising two orthogonal and coplanar sets of microphones, the outputs of the sampling devices being each connected, via a filter, for each of the two sets, as far a first part of these outputs is concerned, to first summator and, as far as a second part of these outputs is concerned, to a second summatot, each of the two summators being connected via a compensating filter to another summator, the output of which is connected to a device for the positional servocontrol of the plane in which the microphones are positioned.