Microphone Array Wall Direction Estimation for Reflection-Aware Audio

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Solution Overview

Problem

Electronic devices struggle with performance degradation due to the presence of acoustically reflective surfaces, affecting speech recognition and sound quality, as reflections from these surfaces confuse sound source localization.

Innovation Solution

The device performs wall direction estimation by detecting direct and reflected sound waves using a microphone array, calculating time delays, and determining the position of acoustically reflective surfaces relative to the device, allowing it to modify audio settings and improve sound source localization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the device uses standard audio processing without wall direction estimation, then the device complexity is low, but the sound source localization accuracy deteriorates due to reflections from acoustically reflective surfaces

Engineering Contradiction:
Improvesound source localization accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs wall direction estimation before sound source localization to pre-characterize the acoustic environment. By detecting acoustically reflective surfaces and determining their positions relative to the device in advance, the system can compensate for reflections during subsequent audio processing, thereby improving localization accuracy without adding complex real-time processing requirements

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system introduces an intermediary processing stage that analyzes audio signals to detect reflections and determine wall directions. This intermediary analysis acts as a bridge between raw audio input and final sound source localization, enabling the system to account for environmental reflections and improve measurement precision without fundamentally changing the core localization algorithm

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If the device ignores reflections from acoustically reflective surfaces, then the sound source localization improves, but the speech recognition performance deteriorates due to lack of environmental adaptation

Engineering Contradiction:
Improvesound source localization accuracyVSAvoidspeech recognition performance
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system applies different processing strategies to different audio signals based on their characteristics. For sound source localization, it ignores reflections from detected wall directions, while for speech recognition, it adapts to the acoustic environment by considering the detected wall positions. This localized quality adjustment allows optimal performance for each function without compromising the other

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts audio processing parameters based on the detected acoustic environment. By continuously estimating wall directions and adapting processing strategies accordingly, the system can optimize speech recognition performance in different environments while maintaining accurate sound source localization through selective reflection ignoring

Inventive Principle:
Principle #15Dynamics

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 method enables accurate determination of reflective surface positions, enhancing sound quality and localization by adjusting audio settings and ignoring reflections, thus improving user experience.

Implementation Method 1

detecting direct and reflected sound waves using a microphone array

Methodology Applied
Scientific EffectSound wave detection: Sound

Implementation Method 2

calculating time delays, and determining the position of acoustically reflective surfaces

Methodology Applied
Scientific EffectTime delay calculation: Time of Flight

Data Source

PatentUS12487356B1Method for wall direction estimation
Publication Date: 2025.12.02 AMAZON TECH INC
  • US12487356B1 patent drawing
  • US12487356B1 patent drawing
  • US12487356B1 patent drawing

AI summary

A system that performs wall direction estimation to determine a position of an acoustically reflective surface relative to a device. For example, the device may detect a direct sound received from an active sound source and a first reflection reflected from a nearby wall. Based on a time delay, the device can estimate a direction and/or distance to the wall. For example, the device determines a time differential of arrival (TDOA) between the direct sound and the first reflection for each microphone in a microphone array. The device combines TDOA values of the entire microphone array into a distance vector, which the device can compare to reference distance data to determine the best wall direction estimate. For example, reference distance values are fixed based on a geometry of the microphone array and the device can identify an azimuth value that is most similar to the distance vector.