Phase Adjustment Filters for Stereo Imaging in Asymmetrical Listening Environments
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Solution Overview
Problem
Existing phase shifting filters for audio reproduction systems are inadequate in addressing the near-side bias problem, particularly in asymmetrical loudspeaker-listener positions and multi-listener scenarios, as they rely on ideal symmetry assumptions and fail to provide spatial robustness.
Innovation Solution
The method involves estimating acoustic transfer functions at multiple spatial positions to determine phase adjustment filters for audio reproduction channels, which reduce inter-loudspeaker differential phase (IDP) across various listener positions, ensuring improved stereo imaging even in complex acoustic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase shifting filters are applied to correct near-side bias, then stereo image quality is improved, but the system fails to provide spatial robustness for multiple listener positions
Solution Approach 1:
The patent segments the listening space into multiple spatial positions and creates separate phase correction filters for each position. By dividing the correction task into position-specific segments, the system achieves precise stereo imaging for each listener location while maintaining overall spatial robustness through the collective coverage of multiple filters.
Solution Approach 2:
The patent creates a universal phase correction system that serves multiple listener positions simultaneously. The set of position-specific filters works together as a universal solution that adapts to different spatial configurations, making the system versatile for multiple scenarios rather than being limited to a single ideal position.
2Reliability
If phase adjustment filters are optimized for ideal symmetrical positions, then near-side bias is corrected, but the system becomes inadequate for asymmetrical loudspeaker-listener positions
Solution Approach 1:
The patent explicitly addresses asymmetrical positions by creating phase correction filters tailored to each specific listener position, regardless of symmetry. Instead of assuming ideal symmetrical conditions, the system embraces asymmetry by measuring and correcting phase differences for each actual listener position, making the solution reliable for real-world asymmetrical configurations.
Solution Approach 2:
The patent changes the parameters of phase correction based on listener position measurements. By measuring acoustic transfer functions at different positions and adjusting phase shift parameters accordingly, the system adapts to asymmetrical positions while maintaining reliable near-side bias correction for each specific configuration.
3Device complexity
If single-position phase correction is applied, then computational complexity is reduced, but IDP cannot be effectively reduced across multiple listener positions
Solution Approach 1:
The patent segments the phase correction task into multiple position-specific filters rather than attempting a single complex multi-position solution. This segmentation reduces the computational complexity of each individual filter while achieving accurate IDP reduction across multiple positions through the collective effect of all filters.
Data Source
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AI summary
There is provided a method and corresponding system for determining phase adjustment filters for an associated sound generating system comprising at least two audio reproduction channels C 1 and C 2 where each of said audio reproduction channels C 1 and C 2 has an input signal and at least one loudspeaker located in a listening environment. The method comprises estimating (S1), for each of said audio reproduction channels C 1 and C 2, an acoustic transfer function at each of M ≥ 1 spatial positions in said listening environment, based on sound measurements at said spatial positions; and determining (S2), based on said acoustic transfer functions, phase adjustment filters F 1 (f) and to be applied, respectively, to said audio reproduction channels C 1 and C 2, to reduce the inter-loudspeaker differential phase, IDP, between said audio reproduction channels C 1 and C 2 in p listener positions.