Planar Loudspeaker Crosstalk Reduction via Digital Filter Decoupling
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Solution Overview
Problem
Existing sound reproduction systems in vehicles face challenges in creating distinct sound zones with minimal crosstalk, as practical implementations of multi-dimensional inverse filters are complex and result in insufficient crosstalk cancellation, especially in automotive applications where high-quality audio is demanded.
Innovation Solution
The use of at least four planar loudspeakers with directional characteristics, each associated with an audio channel, and multi-channel digital filters characterized by transfer matrices representing the inverse of room impulse response matrices, to create separate sound zones in the front and rear portions of a car cabin, effectively reducing crosstalk through directivity and decoupling of sound zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multi-dimensional inverse filters are used for crosstalk cancellation, then crosstalk reduction is improved, but device complexity increases significantly
Solution Approach 1:
The patent divides the car cabin into multiple independent sound zones (front left, front right, rear left, rear right), each with its own audio processing chain. Instead of using a complex multi-dimensional inverse filter for the entire cabin, the system segments the audio reproduction task into separate two-dimensional inverse filter operations for each sound zone, significantly reducing overall system complexity while maintaining effective crosstalk cancellation between zones.
2Object-affected harmful factors
If planar loudspeakers with directional characteristics are used, then sound zone separation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs planar loudspeakers that serve multiple functions: they provide directional sound radiation for sound zone separation, can be mounted in various locations within the car cabin, and work effectively with the multi-channel digital filter system. This multi-functionality allows the same loudspeaker type to be used throughout the system, simplifying the overall manufacturing and installation process despite the advanced acoustic requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces crosstalk, allowing for high-quality, separate sound reproduction in multiple zones within a car cabin, improving the size of the sound zone with sufficient crosstalk damping and enabling effective decoupling of sound zones between the front and rear portions.
Implementation Method 1
at least four planar loudspeakers having a directional characteristics are provided
Implementation Method 2
Theoretical work has shown that crosstalk cancellation is possible using inverse filters
Implementation Method 3
The transfer matrix may represent the inverse of a room impulse response matrix, which includes the transfer functions representing the room impulse responses defined by the at least two loudspeakers and the at least two sound zones
Data Source
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AI summary
A sound reproduction system that capable of providing at least two separate sound zones in one coherent listening room is disclosed. In accordance with one aspect of the present invention the system comprises an audio source which has at least two output channels and provides an audio source signal for each output channel. Each audio channel is associated with one sound zone. The system further comprises at least two planar loudspeakers which have a directional characteristics, wherein each loudspeaker is associated with one audio channel and one sound zone. Each loudspeaker is supplied with a respective loudspeaker signal and radiates a corresponding acoustic signal. Moreover, the system comprises a multi-channel digital filter that receives the audio source signals and provides the loudspeaker signals. The digital filter has a transfer characteristic that is characterized by a transfer matrix. The acoustic signals radiated by the planar loudspeakers superpose to a resulting acoustic signal in each sound zone, wherein the transfer matrix is designed such that, in each sound zone, the resulting acoustic signal substantially corresponds to the audio source signal associated with the same sound zone, and the contribution of audio source signals associated with a different sound zone to the resulting sound signal is minimized.