Equatorial Acoustic Sensor Array for Binaural Rendering

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Solution Overview

Problem

Conventional spherical microphone arrays require a large number of microphones to achieve accurate sound field capture, making them unsuitable for devices with small form factors and increasing costs, complexity, and power consumption.

Innovation Solution

An equatorial acoustic sensor array (EASA) with a reduced number of microphones, arranged in a plane and capable of capturing a sound field's spherical harmonic decomposition, which is then processed to enable binaural rendering and playback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a spherical microphone array (SMA) is used to capture sound fields with direction-independent spatial resolution, then measurement precision is improved, but device complexity and quantity of components increase significantly

Engineering Contradiction:

Improvesound field capture accuracyVSAvoidmicrophone array complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the essential sampling function from the complete spherical microphone array, implementing a simplified equatorial configuration that captures sufficient spatial information for binaural rendering without requiring microphones distributed over the entire spherical surface. This selective extraction maintains measurement precision for the specific application while dramatically reducing device complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a traditional SMA that captures the complete sound field and then processes it, the patent inverts the approach by using an EASA that directly captures only the necessary equatorial sound field information required for binaural rendering. This inversion eliminates unnecessary measurements and processing steps, reducing complexity while maintaining the required measurement precision.

Inventive Principle:

Principle #13The other way round (Inversion)

2Device complexity

If the number of microphones in an SMA is reduced, then device complexity and cost decrease, but measurement precision deteriorates

Engineering Contradiction:

Improvemicrophone array complexityVSAvoidsound field capture accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by concentrating microphone elements specifically in the equatorial plane where they are most needed for binaural rendering applications. Rather than uniformly distributing microphones across the entire sphere, the EASA places sensors only where they provide maximum benefit for the specific application, maintaining measurement precision in the critical horizontal sound field while reducing overall component count.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by capturing only the equatorial portion of the sound field rather than the complete spherical sound field. This partial measurement approach is sufficient for binaural rendering applications, achieving the required measurement precision without the excessive action of capturing and processing the entire spherical sound field with numerous microphones.

Inventive Principle:

Principle #16Partial or excessive action

3Measurement precision

If a large number of microphones are used in an SMA, then sound field capture accuracy is improved, but use of energy and cost increase

Engineering Contradiction:

Improvesound field capture accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the essential equatorial sound field sampling function needed for binaural rendering, eliminating the need for numerous microphones distributed over the entire spherical surface. This extraction maintains measurement precision for the specific application while dramatically reducing the number of active sensors, thereby lowering power consumption and cost.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements partial measurement by capturing only the equatorial sound field information necessary for binaural rendering rather than the complete spherical sound field. This partial action approach achieves sufficient measurement precision with fewer microphones, directly reducing the energy required for signal processing and power consumption of the microphone array.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11564038B1Spherical harmonic decomposition of a sound field detected by an equatorial acoustic sensor array

Publication Date: 2023.01.24 META PLATFORMS TECHNOLOGIES LLC

AI summary

An audio system includes an equatorial acoustic sensor array (EASA) that may be coupled to an object. The audio system is configured to detect, via the EASA, signals corresponding to a portion of a sound field in a local area. The detected signals are converted into a plurality of corresponding abstract representations that describe the portion of the sound field. Effects of scattering of the object are removed from the abstract representations to create adjusted abstract representations. A set of spherical harmonic (SH) coefficients is determined using the adjusted abstract representations. The set of SH coefficients describe an entirety of the sound field. And the set of SH coefficients and head related transfer functions of a user are used for binaural rendering of the reconstructed sound field to the user.