Directional Noise Suppression via Spatial Masking

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Solution Overview

Problem

Microphone array beamforming for directional noise suppression is compromised by sub-optimal microphone placement, leading to grating lobes and restricted frequency bandwidth, particularly in consumer devices where ideal placement is not feasible due to industrial design constraints.

Innovation Solution

A digital signal processing system that includes a microphone array front-end and an intelligent acoustic source localization subsystem using machine learning for speaker identification, which applies a spatial mask to suppress interfering noise while preserving the desired signal, allowing for flexible design of the beam pattern.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional microphone array beamforming is used for directional noise suppression, then noise suppression capability is improved, but sub-optimal microphone placement causes grating lobes that compromise array directionality and restrict operating frequency bandwidth

Engineering Contradiction:

Improvenoise suppression capabilityVSAvoidarray directionality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies digital signal processing techniques to modify the beamforming parameters and spatial filtering characteristics. By changing the processing parameters rather than physical microphone placement, the system achieves improved noise suppression while maintaining array directionality and extending operating frequency bandwidth.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical solution of optimal microphone placement with a digital signal processing system. Instead of physically positioning microphones at ideal locations (which is constrained by industrial design), the system uses DSP algorithms to achieve the desired beamforming and noise suppression performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If traditional microphone array beamforming is used, then directional noise suppression is achieved, but operating frequency bandwidth is restricted due to sub-optimal microphone placement

Engineering Contradiction:

Improvedirectional noise suppressionVSAvoidoperating frequency bandwidth

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The patent modifies the beamforming parameters and spatial filtering characteristics through digital signal processing. This allows the system to achieve directional noise suppression across a broader operating frequency bandwidth without being constrained by sub-optimal microphone placement.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If ideal microphone placement is implemented, then array directionality is improved, but industrial design constraints prevent optimal placement on consumer devices

Engineering Contradiction:

Improvearray directionalityVSAvoidindustrial design feasibility

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the need for ideal physical microphone placement with a digital signal processing system. This allows consumer devices to maintain good array directionality using microphones placed according to industrial design constraints, rather than requiring ideal placement positions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Object-affected harmful factors

If more microphones are added to the array, then noise suppression performance is improved, but device complexity and manufacturing constraints increase

Engineering Contradiction:

Improvenoise suppression performanceVSAvoidmicrophone array complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent achieves improved noise suppression performance by optimizing the beamforming parameters and spatial filtering characteristics through digital signal processing, rather than simply adding more microphones to the array. This approach improves performance while controlling device complexity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11508348B2Directional noise suppression

Publication Date: 2022.11.22 MOTOROLA MOBILITY LLC

AI summary

Systems and methods of providing improved directional noise suppression in an electronic device implement a technique that specifies a direction or speaker of interest, determines the directions corresponding to speakers not lying in the direction of interest, beam forms the reception pattern of the device microphone array to focus in the direction of interest and suppresses signals from the other directions, creating beam formed reception data. A spatial mask is generated as a function of direction relative to the direction of interest. The spatial mask emphasizes audio reception in the direction of interest and attenuates audio reception in the other directions. The beam formed reception data is then multiplied by the spatial mask to generate an audio signal with directional noise suppression.