Adaptive Inverse Filtering for Out-of-Head Sound Localization
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Solution Overview
Problem
Current out-of-head localization processing devices use filters that may not accurately account for individual variations in ear canal transfer characteristics, leading to suboptimal sound localization experiences due to changes in ear shape and fit.
Innovation Solution
An adaptive control system that generates and corrects inverse filters based on real-time sound pickup signals and frequency analysis, ensuring optimal filter coefficients for improved sound localization by convolving spatial acoustic filters with inverse filters to minimize error functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed filter coefficients are used for out-of-head localization processing, then device complexity is reduced, but sound localization accuracy deteriorates due to individual variations in ear canal transfer characteristics
Solution Approach 1:
The patent implements adaptive control that dynamically adjusts filter coefficients based on real-time frequency analysis of sound pickup signals. The adaptation speed is modified according to frequency characteristics, allowing the system to track changes in ear canal transfer characteristics while maintaining computational efficiency through selective adaptation in different frequency bands.
Solution Approach 2:
The system changes filter coefficients adaptively based on measured ear canal transfer characteristics. By modifying the filter parameters according to individual user measurements and real-time frequency analysis, the system achieves accurate sound localization tailored to each user's unique ear anatomy without requiring complex fixed-filter designs.
2Ease of operation
If adaptive control with fixed adaptation speed is used, then ease of operation is improved, but sound localization accuracy deteriorates due to frequency-specific characteristics of ear canal transfer functions
Solution Approach 1:
The patent divides the frequency spectrum into multiple bands and applies different adaptation speeds to each band based on the frequency characteristics of ear canal transfer functions. This segmentation allows the system to handle different frequency regions with appropriate adaptation rates, improving overall accuracy while maintaining operational simplicity through automated frequency-based control.
Solution Approach 2:
The adaptation speed parameter is dynamically modified according to frequency analysis results. The system automatically adjusts the adaptation speed for different frequency components, enabling precise tracking of ear canal characteristics in critical frequency ranges while maintaining stability in less sensitive bands.
3Measurement precision
If real-time filter adjustment is implemented, then sound localization accuracy is improved, but processing time increases due to continuous frequency analysis and adaptive control
Solution Approach 1:
The patent implements periodic frequency analysis and adaptive control updates rather than continuous processing. By periodically analyzing frequency characteristics and adjusting filter coefficients at optimized intervals, the system maintains accurate sound localization while reducing computational load and processing time compared to continuous real-time adjustment.
Data Source
AI summary
An out-of-head localization processing device according to this embodiment includes: a frequency analysis unit configured to perform frequency analysis on an input signal; an inverse filter unit configured to convolve an inverse filter to the input signal and to generate an output signal; a microphone configured to pick up the output signal output from an output unit; an adaptive control unit configured to: calculate an error function based on the input signal and a sound pickup signal; perform adaptive control so that the error function is minimized; and change an adaptation speed according to a result of the frequency analysis, the input signal being a signal to which a predetermined filter coefficient is convolved; and a correction unit configured to correct the inverse filter according to a result of the adaptive control.