ESTIMATION OF SYNTHETIC AUDIO PROTOTYPES

• US 20120099739A1
• Filed: 10/21/2011
• Published: 04/26/2012
• Est. Priority Date: 10/21/2010
• Status: Active Grant

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Hultz, Paul B., Barksdale, Tobe, Dublin, Michael, Walters, Luke C.
• Granted Patent: US 9,078,077 B2
• Time in Patent Office: Days
• US Class Current: 381/92
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04S 2400/05 Generation or adaptation of centre channel in multi-channel audio systems
• CPC Class Codes: H04S 2400/15 Aspects of sound capture and related signal processing for recording or reproduction
• CPC Class Codes: H04S 2420/07 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04S 3/008 in which the audio signals are in digital form, i.e. employing more than two discrete digital channels data reduction aspects thereof based on psychoacoustics G10L19/02
• CPC Class Codes: H04S 3/02 of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other

Abstract

An approach to forming output signals both permits flexible and temporally and/or frequency local processing of input signals while limiting or mitigating artifacts in such output signals. Generally, the approach involves first synthesizing prototype signals for the output signals, or equivalently characterizing such prototypes, for example, according to their statistical characteristics, and then forming the output signals as estimates of the prototype signals, for example, as weighted combinations of the input signals.

Claims

1. A method for forming one or more output signals from a plurality of input signals comprising:

decomposing the input signals into input signal components representing different frequency components at each of a series of times;

determining a characterization of one or more prototype signals from multiple of the input signals, the characterization of the one or more prototype signals comprising a plurality of prototype components representing different frequency components at each of the series of times; and

forming one or more output signals, including forming each output signal as an estimate of a corresponding one of the one or more prototype signals comprising a combination of one or more of the input signals.

2. The method of claim 1 wherein forming the output signal as an estimate of a prototype signal comprises, for each of a plurality of prototype components, forming an estimate as a combination of multiple of the input signal components, including at least some input signal components at a different time or a different frequency than the prototype component being estimated.

3. The method of claim 2 wherein the combination of one or more input signals comprises one or more input signals at times corresponding to each of the series of times.

4. The method of claim 2 wherein forming the estimate as a combination of multiple of the input signal components includes forming a combination of one or more input signal components at a plurality of times preceding each of the series of times for which the output signals are formed.

5. The method of claim 1 wherein forming the output signal as an estimate of a prototype signal comprises applying one or more constraints in determining the combination of the one or more of the input signals.

6. The method of claim 1 further comprising accepting the plurality of input signals from a microphone array.

7. The method of claim 6 further comprising synthesizing the one or more prototype signals according to differences among the input signals and wherein forming the prototype signal according differences among the input signals includes determining a gating value according to gain and/or phase differences and applying the gating value to one or more of the input signals to determine the prototype signal.

8. The method of claim 6 wherein forming one or more output signals includes forming the estimates of the one or more prototype signals according to at least one of a characterization of a response to a desired signal and a characterization of an undesired signal in the signals from the microphone array.

9. The method of claim 8 wherein the characterization of the response to the desired signal or the characterization of the response to the undesired signal comprises transfer function characteristics for said signal.

10. The method of claim 1 wherein determining the characterization of the prototype signals includes determining the prototype signals.

11. The method of claim 1 wherein determining the characterization of the prototype signals includes determining statistical characteristics of the prototype signals.

12. The method of claim 1 wherein determining the characterization of a prototype signal includes forming said data based on a temporally local analysis of the input signals.

13. The method of claim 1 wherein synthesis of a prototype signal includes a gating of one or more of the input signals.

14. The method of claim 1 wherein forming the output signal as an estimate of the prototype includes forming minimum error estimate of the prototype.

15. The method of claim 14 wherein forming the minimum error estimate comprises forming a least-squared error estimate.

16. The method of claim 1 wherein forming an output signal as an estimate of a corresponding one of the one or more prototype signals as a combination of one or more of the input signals including computing estimates of statistics relating the prototype signal and the one or more input signals, and determining a weighting coefficient to apply to each of said input signals.

17. The method of claim 16 wherein the statistics include cross power statistics between the prototype signal and the one or more input signals, and auto power statistics of the one or more input signals.

18. A system for processing a plurality of input signals comprising:

an input processor configured to decompose input signals into input signal components representing different frequency components at each of a series of times;

a prototype generator configured to accept multiple of the input signals and to provide a characterization of a prototype signal the characterization of the one or more prototype signals comprising a plurality of prototype components representing different frequency components at each of the series of times; and

an estimator configured to accept the characterization of the prototype signal and to form an output signal as an estimate of the prototype signal as a combination of one or more of the input signals by estimating.

19. Software tangibly embodied on a computer-readable medium comprising instructions for causing a data processing system to perform functions including:

decomposing input signals into input signal components representing different frequency components at each of a series of times;

determining a characterization of one or more prototype signals from multiple of the input signals, the characterization of the one or more prototype signals comprising a plurality of prototype components representing different frequency components at each of the series of times; and

forming one or more output signals, including forming each output signal as an estimate of a corresponding one of the one or more prototype signals comprising a combination of one or more of the input signals.

20. An audio acquisition system comprising:

an input for receiving a plurality of input signals from a corresponding plurality of microphones;

an input processor configured to decompose a plurality of input signals into input signal components representing different frequency components at each of a series of times;

a prototype generator configured to accept multiple of the input signals and to provide a characterization of a desired prototype signal, the characterization of the one or more prototype signals comprising a plurality of prototype components representing different frequency components at each of the series of times; and

an estimator configured to accept the characterization of the prototype signal and to form an output signal as an estimate of the prototype signal as a combination of one or more of the input signals by estimating, wherein forming the output signal is performed according to a pattern of response of the microphones to a signal from a desired location.