Ambisonic Microphone Interpolation with Distance-Dependent Filtering

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for interpolating ambisonic sound fields from recordings with ambisonic microphones are ineffective, particularly failing to accurately reproduce 6DoF audio in live scenarios, leading to poor spatial audio reproduction and unnatural sound perception.

Innovation Solution

A method involving synchronized recording with distance-dependent filtering and re-balancing of ambisonic components, using a grid of ambisonic microphones with individual synchronization signals and filters that attenuate higher-order components and amplify the 0th order component, ensuring precise spatial sound representation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If existing interpolation methods are used for ambisonic sound fields, then the process is simple, but the spatial audio reproduction quality is poor and sound perception is unnatural

Engineering Contradiction:

Improvespatial audio reproduction accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The interpolation process is segmented into distinct stages: synchronization signal generation, distance calculation, filtering with distance-dependent cutoff frequencies, and re-balancing of ambisonic components. Each stage handles a specific aspect of the problem, improving spatial audio reproduction accuracy while keeping the overall system manageable through modular processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Synchronization signals are generated and applied to all ambisonic microphones before the actual sound recording begins. This preliminary synchronization ensures that all microphones are perfectly aligned in time, which is critical for accurate spatial audio reproduction and enables the subsequent interpolation to work effectively

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If higher-order ambisonic components are retained, then spatial resolution is improved, but irrelevant directivity information and energy inconsistency increase

Engineering Contradiction:

Improvespatial resolutionVSAvoidenergy consistency

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The cutoff frequency parameter is changed dynamically based on the distance between the interpolation point and each microphone. This distance-dependent filtering selectively attenuates higher-order ambisonic components at appropriate frequencies, removing irrelevant directivity information while preserving energy consistency in the reproduced sound field

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Different filtering and re-balancing operations are applied locally to each ambisonic component based on its order and the distance to the interpolation point. Higher-order components receive different treatment than lower-order components, with the filtering and attenuation parameters adapted to the specific spatial context of each component

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If ambisonic microphones are distributed spatially, then 6DoF audio coverage is improved, but synchronization difficulty and processing complexity increase

Engineering Contradiction:

Improve6DoF audio coverageVSAvoidsynchronization complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A centralized processing system acts as an intermediary that receives signals from all spatially distributed ambisonic microphones, performs synchronization based on generated reference signals, calculates distances to interpolation points, and applies coordinated filtering and re-balancing operations. This intermediary approach manages the complexity of synchronizing multiple distributed microphones while enabling comprehensive 6DoF audio coverage

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11638114B2Method, system and computer program product for recording and interpolation of ambisonic sound fields

Publication Date: 2023.04.25 ZYLIA SP ZOO

AI summary

A method of recording ambisonic sound fields with a spatially distributed plurality of ambisonic microphones comprising a step of recording sound signals from plurality of ambisonic microphones a step of converting recorded sound signals to ambisonic sound fields and a step of interpolation of the ambisonic sound fields according to the invention comprises a step of generating synchronizing signals for particular ambisonic microphones for synchronized recording of sound signals from plurality of ambisonic microphones and during the step of interpolation of the ambisonic sound fields it includes filtering sound signals from particular microphones with individual filters having a distance-dependent impulse response having a cut-off frequency fc(dm) depending on distance dm between point of interpolation and m-th microphone applying gradual distance dependent attenuation applying re-balancing with amplification of 0th ordered ambisonic component and attenuating remaining ambisonic components. Invention further concerns recording system and computer program product.