System for communication enhancement in a noisy environment

• US 7,643,641 B2
• Filed: 05/10/2004
• Issued: 01/05/2010
• Est. Priority Date: 05/09/2003
• Status: Active Grant

• Current Assignee: Cerence Inc., Cerence Operating Company (Cerence Inc.)
• Original Assignee: Nuance Communications, Inc. (Microsoft Corporation)
• Inventors: Haulick, Tim, Schmidt, Gerhard Uwe
• Primary Examiner(s): Mei; Xu
• Assistant Examiner(s): Paul; Disler
• Application Number:
  US10/556,232
• Publication Number:
  US 20070053524A1
• Time in Patent Office: 2,066 Days
• Field of Search: 381/86, 381 91- 92, 381 941- 943, 381/94.5, 381/123, 381/122, 381/26, 381/94.7, 381/313, 367118-119, 367/124
• US Class Current: 381/92
• CPC Class Codes: G10L 2021/02082 the noise being echo, reverberation of the speech
• 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 2021/02166 Microphone arrays; Beamforming
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• CPC Class Codes: H04R 2430/23 Direction finding using a sum-delay beam-former
• CPC Class Codes: H04R 2430/25 Array processing for suppression of unwanted side-lobes in directivity characteristics, e.g. a blocking matrix
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

The invention is directed to a method comprising receiving input signals emanating from at least two microphone arrays each comprising at least two microphones, processing the input signals of each microphone array by a beamformer to determine temporal and spatial information about the input signals of each microphone array.

Claims

1. A method for enhancing communication in a noisy environment comprising:

receiving input signals emanating from at least two microphone arrays each comprising at least two microphones; and

processing the input signals of each microphone array by an adaptive wanted signal beamformer and a blocking beamformer, the processing comprising;

determining temporal and spatial information about the input signals of each microphone array;

obtaining a wanted signal from the adaptive wanted signal beamformer;

obtaining a blocking signal from the blocking beamformer; and

deciding whether a signal is transmitted from a wanted signal direction, the deciding comprising;

determining a wanted signal power; and

determining a blocking signal power,

wherein the adaptive wanted signal beamformer is adapted only if no signal is transmitted from the wanted signal direction, which is determined as when the blocking signal power is larger than a predetermined constant times the wanted signal power.

2. The method of claim 1, further comprising detecting speech activity for each microphone array.

3. The method of claim 2, wherein detecting speech activity for a microphone array comprises:

determining a wanted signal power, a blocking signal power, and a background noise signal power, comparing the wanted signal power with the blocking signal power and the background noise signal power.

4. The method of claim 3, further comprising comparing the wanted signal powers of at least two microphone arrays and determining a highest power.

5. The method of claim 2, further comprising applying an attenuation to the processed input signals of a microphone array if no speech activity is detected for the microphone array.

6. The method of claim 5, wherein applying the attenuation is performed adaptively, preferably by varying the attenuation in predetermined time steps between zero attenuation and a predetermined maximum attenuation.

7. The method of claim 1, wherein processing comprises determining a gain control of the input signals for each microphone array.

8. The method of claim 7, wherein determining a gain control is performed adaptively.

9. The method of claim 1, further comprising selecting at least one output channel out of at least two output channels on which the processed signals are to be output.

10. The method of claim 9, wherein selecting the at least one output channel comprises determining an amplification for each selected output channel.

11. A communication system comprising:

at least two microphone arrays each comprising at least two microphones to produce microphone signals;

at least one analog/digital converter having an input for receiving said microphone signals and an output for providing digital microphone signals;

a digital signal processor having an input for receiving the digital microphone signals, the digital signal processor configured to;

process the digital microphone signals of each microphone array by an adaptive wanted signal beamformer and a blocking beamformer, the processing comprising;

determining temporal and spatial information about the microphone signals of each microphone array;

obtaining a wanted signal from the adaptive wanted signal beamformer;

obtaining a blocking signal from the blocking beamformer; and

deciding whether a signal is transmitted from a wanted signal direction, the deciding comprising;

determining a wanted signal power; and

determining a blocking signal power,

wherein the adaptive wanted signal beamformer is adapted only if no signal is transmitted from the wanted signal direction, which is determined as when the blocking signal power is larger than a predetermined constant times the wanted signal power; and

provide processed output signals to at least two loudspeakers.

12. The communication system of claim 11, wherein the digital signal processor is further configured to select at least one loudspeaker out of the at least two loudspeakers on which the processed signals are to be output.

13. A vehicular cabin comprising a communication system according to claim 11 and at least two loudspeakers, wherein each microphone array and each loudspeaker is associated with a passenger seat.