Compact Loudspeaker Array Sound Field Control via Segmented Microphone Zones
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Solution Overview
Problem
Existing sound field control methods for compact loudspeaker arrays are inefficient and costly due to the need for extensive microphone arrays and complex measurement systems, particularly when controlling sound in a limited subspace, and they struggle with precision when dealing with non-spherical array shapes and non-rigid loudspeaker membranes.
Innovation Solution
A method that defines a limited microphone surface and uses visibility criteria to select sufficient microphones for sound field control within a specific reproduction subspace, allowing for efficient sound field synthesis by positioning loudspeakers and microphones to capture free field radiation as a MIMO system, and adjusts filter coefficients to minimize reproduction error, with optional steps for compensating acoustic power in reflective environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive microphone arrays are used to capture sound field radiation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the reproduction space into discrete zones and assigns specific microphones to monitor specific zones, rather than using a comprehensive microphone array to monitor the entire space. This segmentation allows precise measurement of sound fields in each zone with fewer total microphones, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent implements local quality by positioning microphones to specifically monitor sound fields in reproduction zones where loudspeakers are present, rather than uniformly distributing microphones throughout the entire reproduction space. This localized approach ensures adequate measurement precision in critical areas while reducing the overall number of microphones required.
2Measurement precision
If microphones are distributed throughout the entire reproduction space, then sound field control accuracy is improved, but loss of time for measurement and setup increases
Solution Approach 1:
The patent divides the reproduction space into multiple zones and assigns microphones to specific zones based on loudspeaker positions, eliminating the need to deploy microphones throughout the entire space. This segmentation significantly reduces measurement setup time while maintaining control accuracy in the relevant zones.
Solution Approach 2:
The patent applies partial action by monitoring only the portions of the reproduction space that are actually used (zones with loudspeakers) rather than the entire theoretical reproduction space. This partial monitoring approach reduces setup time and complexity while providing sufficient control accuracy for practical applications.
3Device complexity
If model-based control methods are used to describe loudspeaker array radiation, then device complexity is reduced, but manufacturing precision and adaptability worsen due to simplifying assumptions
Solution Approach 1:
The patent uses feedback from microphones positioned in the reproduction zones to measure actual sound field radiation and adjust control signals accordingly. This feedback mechanism compensates for the simplifying assumptions in model-based approaches, maintaining manufacturing precision while keeping the control system relatively simple.
Solution Approach 2:
The system performs self-calibration by using the microphone measurements to automatically adjust and optimize the sound field synthesis without requiring complex pre-characterization or manual calibration procedures. This self-service approach improves precision while maintaining system simplicity.
Data Source
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AI summary
A method for optimizing the design and sound field control of a compact loud-speaker array, which includes a plurality of loudspeakers located on a closed loudspeaker surface and the control of the emitted sound field by the loudspeakers within a limited reproduction subspace, having the steps of capturing the sound field using a plurality of microphones and adjusting filter coefficients that modify the alimentation signals of the loudspeakers to minimize the difference between reproduced signals captured by the microphones and target signals describing a target sound field. A conical reproduction surface encloses a reproduction subspace is defined such that the apex of the conical reproduction surface is within the closed loudspeaker surface. Loud-speakers are positioned on a limited loudspeaker surface and the closed loudspeaker surface. The microphones are located on a limited microphone surface defined by the intersection of the inner volume of the conical reproduction subspace and the closed microphone surface.