Spatial sound steering system

• US 6,185,152 B1
• Filed: 12/23/1998
• Issued: 02/06/2001
• Est. Priority Date: 12/23/1998
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Shen, Albert
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US09/221,664
• Time in Patent Office: 776 Days
• Field of Search: 367/127, 367/118, 367/151, 367/96, 367/87
• US Class Current: 367/118
• CPC Class Codes: G01S 3/80 using ultrasonic, sonic or infrasonic waves
• CPC Class Codes: G01S 3/802 Systems for determining direction or deviation from predetermined direction
• CPC Class Codes: H04N 7/142 Constructional details of the terminal equipment, e.g. arrangements of the camera and the display
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

An apparatus and method for determining directionality of acoustic signals arriving from an acoustic source is disclosed. A plurality of reflectors for modifying the acoustic signals and a transducer located proximate to the reflectors is used. A notch detector detects and identifies spectral notches in the modified acoustic signals. A device then determines the direction of the acoustic source. In one embodiment, a microphone system capable of detecting three-dimensional sound is provided. The microphone system comprises an elliptical-shaped microphone enhancer having at least two reflectors located different distances apart from a microphone located in the center of the ellipse. The reflectors have asymmetric ridges which cause interference patterns in the signals received by the microphone, conceptually analogous to the patterns generated by the pinnae of the human ear.

Claims

1. An apparatus to determine directionality of acoustic signals that arrive from an acoustic source comprising:

a plurality of reflectors to receive and modify acoustic signals to produce modified acoustic signals, the plurality of reflectors having asymmetric ridges which modify the acoustic signals by creating interference patterns in the signals;

a transducer located proximate to the reflectors to receive the modified acoustic signals;

a detector operatively connected to the transducer to detect and identify spectral notches in the modified acoustic signals; and

a device operatively connected to the detector to determine directionality of the acoustic source based upon the identified notches received.

2. An apparatus according to claim 1 wherein at least two of the plurality of reflectors are located different distances from the transducer.

3. An apparatus according to claim 2 wherein a portion of each acoustic signal encounters the asymmetric ridges prior to encountering the transducer causing a delay in time before the portion reaches the transducer.

4. An apparatus according to claim 1 wherein the plurality of reflectors are located on a finite reflecting surface having an elliptical shape, further wherein the transducer is located at the center of the ellipse.

5. An apparatus according to claim 4 wherein the reflectors are made from injection molded plastic having an absorption coefficient of at least about 0.05 at a frequency of from about 100 Hz to about four (4) kHz.

6. An apparatus according to claim 1 wherein the device for determining directionality compares the identified notches to previously detected notches to find common notches associated with a particular spatial direction.

7. An apparatus according to claim 6 further comprising a spectral smoother to eliminate unwanted noise in the acoustic signals.

8. An apparatus according to claim 7 further comprising a camera tracking system operatively connected to the apparatus wherein output from the device can activate the camera tracking system and cause a video camera to be pointed in the direction of the acoustic source.

9. A method for determining directionality of acoustic signals arriving from an acoustic source comprising:

receiving and modifying acoustic signals using a plurality of reflectors, wherein the plurality of reflectors have asymmetric ridges which modify the acoustic signals by creating interference patterns in the signals;

transducing the modified acoustic signals into electrical signals using a transducer located proximate to the reflectors;

determining and identifying spectral notches in the modified acoustic signals using a detector operatively connected to the transducer; and

using a device operatively connected to the detector, determining directionality of the acoustic source based upon the identified notches received.

10. A method according to claim 9 wherein at least two of the plurality of reflectors are located different distances from the transducer.

11. A method according to claim 10 wherein a portion of each acoustic signal encounters the asymmetric ridges prior to encountering the transducer causing a delay in time before the portion reaches the transducer.

12. A method according to claim 9 wherein the plurality of reflectors are located on a finite reflecting surface having an elliptical shape, further wherein the transducer is located at the center of the ellipse.

13. A method according to claim 12 wherein the reflectors are made from injection molded plastic having an absorption coefficient of at least about 0.05 at a frequency of from about 100 Hz to about four (4) kHz.

14. A method according to claim 9 wherein the determination of directionality includes comparing the identified notches to previously detected notches to find common notches associated with a particular spatial direction.

15. A method according to claim 14 further comprising subtracting estimates of unwanted noise from the acoustic signals using a spectral smoother.

16. A method according to claim 15 further comprising using a camera tracking system having a video camera, the camera tracking system operatively connected to the apparatus, wherein output from the spatial estimator activates the camera tracking system, causing the video camera to be pointed in the direction of the acoustic source.

17. A method for determining directionality of a sound source, comprising:

acquiring a stream of acoustic data containing interference from the sound source;

converting the acoustic data into numerical sampling frames;

multiplying each frame by a window function;

generating a Fourier transform for each frame;

searching for spectral notches using the Fourier transform;

finding spectral notches in specific areas corresponding to a specific spatial direction;

looking up in a table of known locations associated with different spectral notches; and

outputting a spatial candidate to a camera motor wherein a camera operatively connected to the camera motor is pointed in the direction of the sound source.

18. A method according to claim 17 wherein the camera records an image associated with the sound source.

19. A microphone system for use in a conference environment where a three-dimensional acoustic source emits acoustic signals from diverse and varying locations within the environment, comprising:

a microphone located at the center of at least one reflecting surface having asymmetric ridges, wherein the acoustic signals which interact with the asymmetric ridges reach the microphone later in time than the acoustic signals which travel a direct path to the microphone, further wherein all acoustic signals reaching the microphone are transduced to electrical signals; and

control circuity configured to analyze the electrical signals to determine an angular orientation of the acoustic source in relation to the microphone.

20. A system according to claim 19 wherein the control circuitry provides information on the angular orientation to a video tracking system having a camera, further wherein the video tracking system causes the camera to transmit an image associated with the acoustic source from a transmitter to a remote receiver.

21. A microphone system according to claim 20 wherein the control circuitry includes an audio compressor which provides a compressed audio signal to the transmitter.

22. A sound steering system comprising:

a microphone enhancer for determining directionality of a sound source, the microphone enhancer comprising at least two reflectors having asymmetric ridges, each reflector located on opposite sides of a microphone; and

a controller coupled to the microphone to receive and transform electrical signals from the microphone into an output signal containing directional information of the sound source.

23. A system according to claim 22 further comprising a camera tracking system having a video camera, the camera tracking system operatively connected to the controller, wherein the controller output signal activates the camera tracking system, causing the video camera to be pointed in the direction of the sound source.

26. The method as recited in claim 23 further comprising a spectral smoother to subtract estimates of unwanted noise from the acoustic source.

24. A computer readable medium having instructions for instructing a computer to perform the method of:

determining and identifying spectral notches in a stream of modified acoustic data from an acoustic source, the acoustic data modified through interaction with two or more reflectors comprised of asymmetric ridges; and

determining directionality of the acoustic source based upon the identified notches received.

27. A method according to claim 24 further comprising smoothing the modified acoustic signal with a spectral smoother.

28. A method according to claim 24 wherein the acoustic source is a microphone.

25. A method for instructing a computer using a computer readable medium having instructions, comprising the steps of:

determining and identifying spectral notches in a stream of modified acoustic data from an acoustic source, the acoustic data modified through interaction with two or more reflectors comprised of asymmetric ridges; and

determining directionality of the acoustic source based upon the identified notches received.

29. A method according to claim 25 further comprising smoothing the modified acoustic signal with a spectral smoother.

30. A method according to claim 25 wherein the acoustic source is a microphone.