Sound Pickup Signal Correction for Rotating Microphone Arrays

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Solution Overview

Problem

When an omnidirectional sound field is recorded using an annular or spherical microphone array attached to a moving body, the movement causes rotation and blurring, leading to an inappropriate sound field regeneration and potential sound-induced sickness during playback from a free viewpoint.

Innovation Solution

A sound processing device with a correction unit that adjusts the sound pickup signal based on directional information, performing spatial frequency corrections in spherical harmonics to account for the microphone array's orientation and movement, ensuring accurate sound field regeneration regardless of the viewer's viewpoint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an omnidirectional sound field is recorded using a mobile microphone array, then the sound field can be captured from multiple viewpoints, but the movement causes rotation and blurring that degrade sound field quality

Engineering Contradiction:

Improveviewpoint flexibilityVSAvoidsound field accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system uses directional information (azimuth and elevation angles) as feedback to detect the microphone array's orientation during recording. This feedback is then used to correct the sound field data, allowing the system to compensate for movement-induced rotation and blurring, thereby maintaining sound field accuracy while enabling mobile recording from multiple viewpoints

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the parameters of the sound field data by applying corrections based on directional information. Specifically, it adjusts the spatial frequency spectrum and spherical harmonics coefficients according to the measured azimuth and elevation angles, transforming the raw mobile recording data into corrected sound field data that accurately represents the original sound sources despite microphone array movement

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the microphone array is attached to a moving body for free viewpoint playback, then viewer flexibility is improved, but rotation and blurring occur causing inappropriate sound field regeneration

Engineering Contradiction:

Improveviewing flexibilityVSAvoidsound field regeneration accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary correction of the sound field data during the recording phase by applying directional information corrections to the spatial frequency spectrum and spherical harmonics coefficients. This preliminary action ensures that the stored sound field data is already corrected for rotation and blurring, enabling reliable sound field regeneration during playback regardless of the original microphone array orientation or the viewer's chosen viewpoint

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If spatial frequency correction is applied using directional information, then sound field accuracy is improved, but processing complexity increases

Engineering Contradiction:

Improvesound field accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system replaces complex mechanical stabilization mechanisms with a computational approach. Instead of physically stabilizing the microphone array during recording, it uses signal processing to correct the sound field data mathematically. The correction involves transforming the spatial frequency spectrum and adjusting spherical harmonics coefficients based on directional information, achieving high sound field accuracy through algorithms rather than mechanical means

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11265647B2Sound processing device, method and program

Publication Date: 2022.03.01 SONY GROUP CORP

AI summary

A sound processing device is provided with a correction unit that corrects a sound pickup signal. The sound pickup signal is obtained by picking up a sound with a microphone array. The correction unit corrects the sound pickup signal based on directional information that indicates a direction of the microphone array in spherical coordinates, during the picking up of the sound.