Acoustic Direction Detection via Cross-Correlation Convolution

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Solution Overview

Problem

Existing methods for determining the direction of an acoustic source in video conferencing systems are hindered by noise generated by microphones, requiring expensive high-quality microphones for accurate angle determination.

Innovation Solution

A method and system using a pair of symmetrically arranged microphone elements to calculate cross correlations and convolve these signals to determine the direction of an acoustic source, improving signal-to-noise ratio and allowing for the use of less expensive microphones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single pair of microphones is used for direction determination, then the system is simple and inexpensive, but noise from the microphones degrades the accuracy of angle determination

Engineering Contradiction:

Improveangle determination accuracyVSAvoidmicrophone self-noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent combines the outputs of multiple cross-correlation calculations from different microphone pairs through convolution. By merging the directional information from multiple pairs (first pair giving first cross-correlation signal, second pair giving second cross-correlation signal), the system achieves better noise immunity and more accurate angle determination than any single pair could provide alone.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple pairs of microphones are used to improve signal-to-noise ratio, then direction determination accuracy improves, but the device complexity and cost increase

Engineering Contradiction:

Improvedirection determination reliabilityVSAvoidmicrophone array complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the need for physically complex microphone arrays with a signal processing approach. Instead of using many microphones arranged in complex geometries, the system uses multiple simple pairs of microphones and processes their signals through cross-correlation and convolution operations, achieving high reliability through mathematical processing rather than mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If high-quality expensive microphones are used, then noise is reduced and angle determination is accurate, but the system cost increases significantly

Engineering Contradiction:

Improveangle determination accuracyVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent enables the use of cheaper, lower-quality microphones by compensating for their noise characteristics through signal processing. Instead of relying on expensive high-quality microphones to provide clean signals, the system uses multiple pairs of inexpensive microphones and extracts accurate directional information through cross-correlation and convolution, making the overall system more cost-effective.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the accuracy and reliability of determining the direction of an acoustic source, enabling effective automatic camera pointing in video conferencing without the need for expensive microphones, and improves performance in noisy environments.

Implementation Method 1

receiving acoustic signals originating from an acoustic source at a first pair of microphone elements

Methodology Applied

Scientific EffectSound: Sound

Implementation Method 2

calculating, with a processor device, a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal

Methodology Applied

Scientific EffectCross correlation:

Implementation Method 3

calculating, with the processor device, a direction between the detection point and the acoustic source based on a convolution of the first cross correlation signal by the second cross correlation signal

Methodology Applied

Scientific EffectConvolution:

Data Source

PatentUS8848030B2Method and system for determining a direction between a detection point and an acoustic source

Publication Date: 2014.09.30 CISCO TECHNOLOGY INC

AI summary

A method including: receiving acoustic signals originating from an acoustic source at a first pair of microphone elements, arranged symmetrically about a detection point; calculating, with a processor device, a cross correlation of signals provided by the first pair of microphone elements, resulting in a first cross correlation signal; receiving the acoustic signals originating from the acoustic source at a second pair of microphone elements, arranged symmetrically about the detection point; calculating, with the processor device, a cross correlation of signals provided by the second pair of microphone elements, resulting in a second cross correlation signal; and calculating, with the processor device, a direction between the detection point and the acoustic source based on a convolution of the first cross correlation signal by the second cross correlation signal.