Local Wave Field Synthesis Loudspeaker Drive Control
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Solution Overview
Problem
Existing multi-zone sound reproduction techniques face challenges in controlling sound intensity orientation and practical implementation, particularly when using real loudspeakers arranged on a 2D plane, as they often require uniform geometries and fail to optimize sound fields effectively in real setups with physical microphones.
Innovation Solution
A local wave field synthesis apparatus that determines desired sound pressures and particle velocity vectors at control points on contours around audio zones, jointly optimizing these parameters to generate drive signals for loudspeakers, allowing for personalized sound reproduction by optimizing sound pressure and particle velocity vectors on contours rather than within listening areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control points are distributed in the entire interior of local listening areas, then sound field optimization is improved, but practical implementation becomes impractical due to free-field assumption limitations and physical microphone constraints
Solution Approach 1:
The patent segments the listening area by placing control points only on the boundary contours rather than distributing them throughout the entire interior volume. This reduces the number of control points from a 3D distribution to a 2D boundary distribution, making the system practically implementable with physical microphones while still achieving effective sound field control through boundary-based optimization.
Solution Approach 2:
The patent transitions from a 3D volume-based control point distribution to a 2D boundary-based distribution. By placing control points on the contours (surfaces) surrounding listening areas rather than throughout the interior volumes, the system reduces dimensional complexity and makes the setup practical for real-world implementations with physical microphones.
2Measurement precision
If pressure matching is used to control acoustic pressure, then acoustic contrast between zones is improved, but sound intensity orientation control is lost
Solution Approach 1:
The patent merges pressure matching with energy optimization by imposing a constraint on sound energy while optimizing acoustic pressure. This combination allows the system to achieve desired acoustic contrast between listening areas through pressure control while simultaneously maintaining control over sound intensity orientation through the energy constraint, thus resolving the trade-off between the two control aspects.
3Measurement precision
If regular geometries of transducer arrangement are required, then analytic description of wave fields is improved, but flexibility with respect to transducer setup is reduced
Solution Approach 1:
Instead of requiring the transducer array to conform to regular geometries for analytic descriptions, the patent inverts the approach by placing control points on arbitrary boundary contours that adapt to the actual listening area geometry. This allows the use of measured Room Impulse Responses with real loudspeakers in flexible, non-regular arrangements while maintaining accurate sound field control through the boundary-based optimization framework.
Data Source
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AI summary
A local wave field synthesis apparatus (200) for driving an array of loudspeakers with drive signals to generate one or more local wave fields at one or more audio zones, the apparatus includes a determination module (40, 210) for determining desired sound pressures and desired particle velocity vectors at a plurality of control points, a computation module (60, 212) for computing sound pressures and particle velocity vectors at the plurality of control points based on a set of filter parameters, an optimization module (220) for computing an optimum set of filter parameters by jointly optimizing computed sound pressures towards the desired sound pressures and computed particle velocity vectors towards the desired particle velocity vectors, and a generator module (220) for generating the drive signals based on the optimum set of filter parameters, wherein the plurality of control points are located on one or more contours around the one or more audio zones.