Audio Signal Processing for Half-Cylinder Beam Directivity
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Solution Overview
Problem
Existing audio signal processing technologies for non-planar transducer arrays, such as those on curved surfaces, face limitations in controlling beam directivity and generating sound fields with precise directional patterns, especially for surfaces of a half revolution like a half cylinder, where conventional beamforming methods are not applicable.
Innovation Solution
The development of an audio signal processing apparatus that employs extended mode matching beamforming on a surface of a half revolution, utilizing a filter unit, scaling units, and adders to generate output audio signals with defined beam directivity patterns by applying gain coefficients, and includes a bass enhancement unit for improved low-frequency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional beamforming methods are used for non-planar transducer arrays, then the system can output audio signals, but the beam directivity control and sound field generation precision are insufficient
Solution Approach 1:
The patent extends mode matching beamforming from planar to non-planar surfaces by changing the geometric parameters of the transducer array configuration. The method adapts the beamforming algorithm to accommodate curved surfaces (cylindrical, spherical, conical) by modifying the coordinate system and mathematical models used in conventional planar beamforming, thereby achieving precise beam directivity control on non-planar surfaces.
Solution Approach 2:
The patent segments the complex non-planar surface into multiple zones or regions, each with its own local coordinate system and beamforming parameters. This allows the application of mode matching beamforming to different portions of the curved surface independently, maintaining precision while adapting to the overall non-planar geometry.
2Adaptability or versatility
If mode matching beamforming is applied to cylindrical surfaces, then beam directivity can be controlled, but the method is not applicable to surfaces of a half revolution
Solution Approach 1:
The patent extends the beamforming method from two-dimensional cylindrical surfaces to three-dimensional surfaces of a half revolution by introducing additional spatial dimensions and corresponding mathematical transformations. This dimensional extension allows the method to handle the increased geometric complexity while maintaining beam directivity precision through appropriate coordinate transformations and mode matching calculations.
Data Source
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AI summary
The invention relates to an audio signal processing apparatus (100) for processing an input audio signal (101), comprising a filter unit (103) comprising a plurality of filters (103a-u), each filter (103a-u) configured to filter the input audio signal (101) to obtain a plurality of filtered audio signals (105), each filter (103a-u) designed according to an extended mode matching beamforming applied to a surface of a half revolution, the surface partially characterizing a loudspeaker enclosure shape, a plurality of scaling units (107a-v), each scaling unit (107a-v) configured to scale the plurality of filtered audio signals (105) using a plurality of gain coefficients to obtain a plurality of scaled filtered audio signals (108), and a plurality of adders (109a-w), each adder (109a-w) configured to combine the plurality of scaled filtered audio signals (108), thereby providing an output audio signal (111) for producing a sound field having a beam directivity pattern defined by the plurality of gain coefficients. Moreover, the invention relates to a sound emission apparatus (120).