HRTF Individualization for Hearing Devices
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Solution Overview
Problem
Current hearing devices use generic or idealized head-related transfer functions (HRTFs) for spatialization cues, which are suboptimal for individual users, leading to inaccuracies in sound source localization, as they do not account for the unique head and ear morphology of each person.
Innovation Solution
A hearing system that includes motion tracking and HRTF individualization circuitry to modify the minimum phase and all-pass components of the HRTF based on user motion, allowing for interactive calibration to match the individual's HRTF, thereby enhancing sound localization in three dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If generic or idealized HRTFs are used for spatialization cues, then the device complexity is reduced and ease of manufacture is improved, but the sound source localization accuracy deteriorates because they do not account for individual head and ear morphology
Solution Approach 1:
The HRTF is made dynamically adjustable rather than fixed. The system allows real-time modification of HRTF parameters (minimum phase and all-pass components) based on individual user characteristics determined through motion tracking and calibration procedures, enabling the spatialization cues to adapt to each user's unique head and ear morphology
Solution Approach 2:
The system incorporates feedback loops where the user's actual perceived sound location is compared against the virtual source location. Motion tracking circuitry monitors user head movements and perceived location, and this feedback is used to iteratively refine and individualize the HRTF parameters, continuously improving localization accuracy
Solution Approach 3:
The invention modifies specific parameters of the HRTF (minimum phase component associated with vertical localization and all-pass component associated with horizontal localization) to individualize the transfer function. By adjusting these parameters based on measured user characteristics, the system achieves accurate sound localization without requiring complete redesign of the HRTF framework
2Adaptability or versatility
If generic HRTFs are used, then the ease of operation is improved and setup time is reduced, but the adaptability to individual users deteriorates, resulting in suboptimal spatialization for each person
Solution Approach 1:
The system performs preliminary HRTF individualization through calibration procedures that capture user-specific characteristics before normal operation. Motion tracking and initial calibration measurements are conducted in advance to establish baseline HRTF parameters, reducing the need for continuous adjustment during use
Solution Approach 2:
The HRTF individualization process is designed to be user-friendly and partially automated, allowing users to participate in their own calibration through simple motion tracking tasks. The system automatically processes the collected data and adjusts HRTF parameters without requiring expert intervention, making the individualization process accessible to end users
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
A hearing system includes one or more hearing devices configured to be worn by a user. Each hearing device includes a signal source that provides an input electrical signal representing a sound of a virtual source. A filter implements a head related transfer function (HRTF) to add spatialization cues associated with a virtual location of the virtual source to the electrical signal and outputs a filtered electrical signal that includes the spatialization cues. A speaker of the hearing device converts the filtered electrical signal into an acoustic signal and plays the acoustic signal to the user. The system includes motion tracking circuitry that tracks motion of the user as the user moves in a direction of a perceived location that the user perceives to be the virtual location of the virtual source. Head related transfer function (HRTF) individualization circuitry determines a difference between the virtual location and the perceived location in response to the motion of the user. The HRTF individualization circuitry individualizes the HRTF based on the difference.