Dual Omnidirectional Microphone Array Virtual Directional Beamforming

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Solution Overview

Problem

Conventional multi-microphone noise suppression systems suffer from poor noise cancellation performance and significant speech distortion due to limitations in the number of noise sources that can be removed, primarily because they attempt to 'steer' nulls to the strongest noise sources, which is not effective for multiple noise sources.

Innovation Solution

A dual omnidirectional microphone array (DOMA) is used to form two distinct virtual directional microphones with similar noise responses and dissimilar speech responses, allowing for effective noise suppression without distorting speech by using an adaptive filter and Voice Activity Detector (VAD) algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional multi-microphone systems steer nulls to strongest noise sources, then noise cancellation performance improves for single noise source, but performance deteriorates for multiple noise sources and speech distortion increases

Engineering Contradiction:

Improvenoise cancellation performanceVSAvoideffectiveness against multiple noise sources

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The system segments the noise suppression task by creating multiple virtual microphones from two physical omnidirectional microphones. Each virtual microphone is configured with different beamforming weights to target different spatial regions, allowing simultaneous suppression of multiple noise sources without the limitations of conventional single-null steering approaches

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from the conventional approach of steering nulls in the spatial domain to creating virtual microphones with different directional responses. This dimensional transformation allows the system to achieve multiple noise suppression capabilities simultaneously by varying the virtual microphone configurations rather than sequentially steering nulls

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If directional microphones are used to reduce environmental noise, then noise suppression improves, but speech distortion increases

Engineering Contradiction:

Improveenvironmental noise reductionVSAvoidspeech distortion

Core Design Contradiction:

Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The system creates virtual copies of directional microphone responses through signal processing of two omnidirectional microphones. These virtual directional microphones provide the noise rejection benefits of physical directional microphones while avoiding the speech distortion issues through adaptive beamforming and voice activity detection

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The system dynamically adjusts the beamforming parameters and virtual microphone configurations based on voice activity detection and noise characteristics. This allows optimization of the balance between noise suppression and speech preservation by changing the weighting parameters adaptively rather than using fixed directional patterns

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If more physical microphones are added to handle multiple noise sources, then noise cancellation capability improves, but device complexity increases

Engineering Contradiction:

Improvemultiple noise source suppressionVSAvoidmicrophone array complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Two omnidirectional microphones serve multiple functions simultaneously: they capture speech, detect noise from multiple directions, and generate multiple virtual directional microphones through signal processing. This multi-functionality eliminates the need for additional physical microphones while achieving suppression of multiple noise sources

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces virtual microphones as intermediary elements that mediate between the two physical omnidirectional microphones and the noise suppression objective. These virtual microphones provide directional selectivity without requiring physical directional microphone arrays, reducing complexity while maintaining effectiveness

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20240129660A1Forming virtual microphone arrays using dual omnidirectional microphone array (DOMA)

Publication Date: 2024.04.18 JAWBONE INNOVATIONS LLC

AI summary

A dual omnidirectional microphone array noise suppression is described. Compared to conventional arrays and algorithms, which seek to reduce noise by nulling out noise sources, the array of an embodiment is used to form two distinct virtual directional microphones which are configured to have very similar noise responses and very dissimilar speech responses. The only null formed is one used to remove the speech of the user from V2. The two virtual microphones may be paired with an adaptive filter algorithm and VAD algorithm to significantly reduce the noise without distorting the speech, significantly improving the SNR of the desired speech over conventional noise suppression systems.