Microphone Array AGC Using 3D Position Feedback

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Solution Overview

Problem

Current automatic gain control systems in audio conferencing fail to provide consistent performance in managing wide dynamic range audio signals and ambient sound levels, leading to inconsistent user experiences due to heuristic-based approaches that lack deterministic control over microphone arrays.

Innovation Solution

The system utilizes positional 3D spatial sound power information to deterministically adjust the microphone array gains in real-time, based on the measured position of sound sources and known path loss calculations, thereby maintaining consistent volume levels and ambient sound performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If heuristic-based automatic gain control techniques are used to manage wide dynamic range audio signals, then the system can operate without knowing sound source positions, but the performance becomes non-deterministic and inconsistent

Engineering Contradiction:

Improveability to handle unknown sound source positionsVSAvoidconsistency of audio performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system uses feedback from the position processor that provides real-time sound source position information to the automatic gain control circuit. This feedback loop allows the AGC to make deterministic adjustments based on actual measured positions rather than operating blindly with heuristic assumptions, thereby achieving both adaptability to position changes and consistent reliable performance

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

A position processor acts as an intermediary between the microphone array and the automatic gain control circuit. This intermediary component processes the raw microphone signals to determine sound source positions and provides this positional information to the AGC circuit, enabling the AGC to operate deterministically with accurate position data without requiring direct access to complex position detection logic

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If automatic gain control adjusts gain to normalize signal levels, then audio signals within sufficient range can propagate through the system, but ambient sound levels also track in proportion causing warbling and inconsistent sound levels

Engineering Contradiction:

Improvesignal propagation consistencyVSAvoidstability of ambient sound levels

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The system applies different gain control strategies to different components of the audio signal. The automatic gain control circuit adjusts gain locally for the desired sound source signals based on their measured positions, while separately maintaining ambient sound levels through a different control mechanism. This local differentiation allows signal normalization without proportional ambient sound tracking, eliminating warbling effects

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The audio processing is segmented into separate functions: position detection for sound sources, gain calculation based on position, and selective application of gain to sound source signals versus ambient signals. This segmentation allows independent control of signal levels and ambient levels, preventing the coupled behavior where ambient sounds track with signal gain adjustments

Inventive Principle:

Principle #1Segmentation

3Device complexity

If post-processing automatic gain control is applied isolated from microphone processing logic, then the system architecture remains simple, but the AGC lacks knowledge of sound source position and must operate on assumptions

Engineering Contradiction:

Improvesimplicity of system architectureVSAvoidloss of position information for gain control

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The system performs preliminary position detection and analysis in the position processor before the automatic gain control stage. By determining sound source positions upstream in the signal processing chain, the system prepares and provides position information to the AGC circuit in advance, enabling the post-processing AGC to operate with full position awareness while maintaining the benefit of separated processing stages

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3783914B1Method, apparatus and computer-readable media utilizing positional information to derive AGC output parameters for a microphone array

Publication Date: 2025.04.02 NUREVA INC

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AI summary

Method and apparatus for automatic gain control utilizing sound source position information in a shared space having a plurality of microphones and a plurality of sound sources. Sound signals are received from the microphones. One or more processors locate position information corresponding to each of the sound sources. The processor(s) determine the distance to each of the sound sources from each of the microphones. The processor(s) define a predetermined gain weight adjustment for each of the microphones. The processor(s) apply the defined weight adjustments to the microphones to achieve a consistent volume of the desired plurality of sound sources. The processor(s) maintain a consistent ambient sound level regardless of the position of the sound sources and the applied gain weight adjustments. The processor(s) output a summed signal of the sound sources at a consistent volume with a constant ambient sound level across the plurality of sound source positions.