CO-TALKER NULLING FOR AUTOMATIC SPEECH RECOGNITION SYSTEMS

• US 20150127338A1
• Filed: 11/07/2013
• Published: 05/07/2015
• Est. Priority Date: 11/07/2013
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Inventors: Reuter, Mike
• Granted Patent: US 9,431,013 B2
• Time in Patent Office: Days
• US Class Current: 704/233
• CPC Class Codes: G10L 15/20 Speech recognition techniques specially adapted for robustness in adverse environments, e.g. in noise, of stress induced speech G10L21/02 takes precedence
• 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 21/0316 by changing the amplitude
• CPC Class Codes: H04R 1/08 Mouthpieces; Microphones; Attachments therefor
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2430/20 Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic H04R2203/12 takes precedence
• 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

Speech from a driver and speech from a passenger in a vehicle is selected directionally using two or more microphones. Samples of speech from a driver and picked up by a first microphone are delayed until samples of the speech picked up by a second microphone is in phase with the speech picked up by the first microphone. Samples of a passenger'"'"'s speech and picked up by the second microphone are delayed until samples of the passenger'"'"'s speech picked up by the first microphone are out-of-phase with the speech picked up by the second microphone.

Claims

1. In a vehicle having a driver and a passenger and first and second microphones, which are spatially separated from each other by a distance of at least twelve inches, both microphones being capable of detecting sounds from both the passenger and driver, a method for selectively detecting sounds from the driver and suppressing sounds from the passenger, the method comprising:

selectively detecting at a first microphone, a first sample of a sound from the driver, the first sample of the sound from the driver comprising a first frequency component, the first sample of the sound from the driver being a sample of the first frequency component at a first phase angle;

selectively detecting at a second microphone, a second sample of the sound from the driver, the second sample of the sound from the driver comprising the first frequency component, said second sample being a sample of the first frequency component at a second phase angle;

storing the first sample for a first predetermined length of time to provide a delayed first sample, the first predetermined length of time selected such that the phase angles of the delayed first sample and second phase angle are substantially equal to each other; and

combining the delayed first sample and the second sample.

2. The method of claim 1, further comprising the steps of:

selectively detecting at a first microphone, a first sample of a sound from the passenger, the first sample of the sound from the passenger comprising a second frequency component, the first sample of the sound from the passenger being a sample of the second frequency component at a third phase angle;

selectively detecting at a second microphone, a second sample of the sound from the passenger, the second sample of the sound from the passenger comprising the second frequency component, the second sample being a sample of the second frequency component at a fourth phase angle;

storing the first sample of the sound from the passenger for a second predetermined length of time to provide a delayed first sample of the sound from the passenger, the second length of time being selected such that the phase angle of the delayed first sample of the sound from the passenger and the fourth phase angle are out of phase relative to each other; and

combining the first delayed sample of the sound from the passenger and the second sample of the sound from the passenger whereby sound from the passenger that is detected at the first microphone substantially cancels sound from the passenger that is detected at the second microphone.

3. The method of claim 2, wherein the second length of time is selected such that the phase angle of the delayed first sample of the sound from the passenger and the fourth phase angle are about one-hundred eighty degrees out of phase relative to each other.

4. The method of claim 2, wherein the step of selectively detecting a second sample occurs a third predetermined length of time after occurrence of the step of selectively detecting a first sample.

5. The method of claim 2, wherein the third predetermined length of time is substantially equal to an integer multiple of the length of time required for one wavelength of the first frequency component to travel between the first microphone and second microphone.

6. The method of claim 1, wherein selectively detecting samples of sounds at the first and second microphones directionally selects sounds from at least one of the driver and passenger.

7. An apparatus for a vehicle having a driver and a passenger and first and second microphones, which are spatially separated from each other by a distance of at least twelve inches, both microphones being capable of detecting sounds from both the passenger and driver, the apparatus configured to selectively detect sounds from the driver and suppress sounds from the passenger, the apparatus comprising:

a digital signal processor;

a non-transitory memory device coupled to the digital signal processor and storing program instructions, which when executed cause the digital signal processor to;

selectively detect at a first microphone, a first sample of a sound from the driver, the first sample of the sound from the driver comprising a first frequency component, the first sample of the sound from the driver being a sample of the first frequency component at a first phase angle;

selectively detect at a second microphone, a second sample of the sound from the driver, the second sample of the sound from the driver comprising the first frequency component, said second sample being a sample of the first frequency component at a second phase angle;

store the first sample for a first predetermined length of time to provide a delayed first sample, the first predetermined length of time selected such that the phase angles of the delayed first sample and second phase angle are substantially equal to each other; and

combine the delayed first sample and the second sample.

8. The apparatus of claim 7, wherein the non-transitory memory device stores additional program instructions, which when executed cause the processor to:

selectively detect at the first microphone, a first sample of a sound from the passenger, the first sample of the sound from the passenger comprising a second frequency component, the first sample of the sound from the passenger being a sample of the second frequency component at a third phase angle;

selectively detect at the second microphone, a second sample of the sound from the passenger, the second sample of the sound from the passenger comprising the second frequency component, the second sample being a sample of the second frequency component at a fourth phase angle;

store the first sample of the sound from the passenger for a second predetermined length of time to provide a delayed first sample of the sound from the passenger, the second length of time being selected such that the phase angle of the delayed first sample of the sound from the passenger and the fourth phase angle are out of phase relative to each other; and

combine the first delayed sample of the sound from the passenger and the second sample of the sound from the passenger whereby sound from the passenger that is detected at the first microphone substantially cancels sound from the passenger that is detected at the second microphone.

9. The apparatus of claim 8, wherein the digital signal processor executes program instructions to select the second length of time such that the phase angle of the delayed first sample of the sound from the passenger and the fourth phase angle are about one-hundred eighty degrees out of phase relative to each other.

10. The apparatus of claim 8, wherein the digital signal processor is configured such that detecting a second sample occurs a third predetermined length of time after occurrence of the step of selectively detecting a first sample.

11. The apparatus of claim 8, wherein the digital signal processor is configured such that the third predetermined length of time is substantially equal to an integer multiple of the length of time required for one wavelength of the first frequency component to travel between the first microphone and second microphone.

12. The apparatus of claim 8, wherein the digital signal processor is configured such that selectively detecting samples of sounds at the first and second microphones directionally selects sounds from at least one of the driver and passenger.