HRTF Generation via Per-Object Minimum Phase Interpolation
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Solution Overview
Problem
Current methods for generating head-related transfer functions (HRTFs) are inadequate for accurate sound localization in immersive audio experiences, as they are user-specific, time-consuming to measure, and prone to distortions, and often lack definitions for various positions, leading to impractical surround sound systems and user variability.
Innovation Solution
The implementation of a per-object minimum phase interpolation (POMP) method, which interpolates the minimum phase components of HRTFs and calculates interaural time delay independently for each audio channel, allowing for the generation of effective HRTFs for specific sound source positions, even where no HRTF is defined, by selecting and combining existing HRTFs based on proximity and radial distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete HRTFs are provided for specific positions, then sound localization accuracy is improved for those positions, but no HRTF is defined for positions between the discrete points
Solution Approach 1:
The patent creates virtual HRTFs for undefined positions by copying and interpolating between existing measured HRTFs. The system generates intermediate HRTFs through mathematical interpolation of magnitude and phase components from neighboring measured HRTFs, effectively creating copies adapted for positions where no direct measurement exists.
Solution Approach 2:
The patent changes parameters of existing HRTFs through interpolation of magnitude and phase components. By adjusting these parameters based on the spatial relationship between measured positions and target positions, the system generates appropriate HRTFs for intermediate positions without requiring new measurements.
2Measurement precision
If HRTFs are measured for each user, then localization accuracy is improved, but the process is time consuming and expensive
Solution Approach 1:
The patent makes a single user's measured HRTFs universally applicable to other users through the POMP interpolation method. The system processes HRTFs from one user to generate effective HRTFs for other users by interpolating magnitude and phase components, eliminating the need for time-consuming measurements for each individual user.
Solution Approach 2:
The patent creates virtual HRTFs for users who haven't undergone measurement by copying and adapting HRTFs from other users. The interpolation process generates user-specific HRTFs by combining magnitude information from one user with phase information, effectively creating a copy tailored to the target user's spatial characteristics.
3Measurement precision
If HRTFs are measured in a physical environment, then real-world accuracy is improved, but distortions occur due to objects and positioning issues
Solution Approach 1:
The patent extracts only the essential magnitude and phase components from measured HRTFs, separating them from environmental distortions. By processing these extracted components through interpolation, the system generates clean virtual HRTFs that eliminate harmful environmental factors while preserving the fundamental spatial acoustic characteristics.
Solution Approach 2:
The patent introduces mathematical interpolation as an intermediary process between measured HRTFs and final output. This intermediary step filters out environmental distortions while preserving essential spatial information, creating a cleaner representation of acoustic properties without direct contamination from physical environment objects.
4Device complexity
If generalised HRTFs are used for groups of users, then implementation complexity is reduced, but localization accuracy deteriorates due to user variability
Solution Approach 1:
The patent dynamically changes HRTF parameters through interpolation based on the target user's characteristics and the desired sound source position. By adjusting magnitude and phase parameters individually for each user and position combination, the system maintains high localization accuracy while keeping the overall system relatively simple, avoiding the need for extensive individual measurements.
Data Source
AI summary
A system for generating a head-related transfer function, HRTF, for a given position with respect to a listener, the system comprising a dividing unit operable to divide each of a plurality of existing HRTFs, each corresponding to a respective plurality of positions, into first and second components, an interaural time difference determination unit operable to determine an interaural time difference expected by a user for a sound source located at the given position in dependence upon the respective first components, an interpolation unit operable to generate an interpolated second component by interpolating generated second components using a weighting dependent upon the respective positions for the corresponding HRFTs and the given position, and a generation unit operable to generate an HRTF for the given position in dependence upon the interaural time difference and the interpolated second component.