HRTF Frequency Region Tuning for Vertical Sound Localization

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Solution Overview

Problem

Existing methods for simulating sound source perception using head-related transfer functions (HRTFs) are challenging due to variations in ear shapes among users, often leading to distorted audio experiences and difficulty in accurately adjusting HRTFs for desired outcomes.

Innovation Solution

Adjusting the amplitude of specific frequency regions within the contralateral HRTF, independent of the ipsilateral HRTF, to simulate vertical displacement of a sound source, without requiring personalized adjustments for each user, thereby reducing processing demands and distortion risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual adjustment of HRTF elements is performed to simulate vertical displacement, then perceived sound source position can be adjusted, but the complexity of adjustment increases and sound distortion risk increases due to variations in ear shapes

Engineering Contradiction:

Improveperceived sound source positionVSAvoidHRTF adjustment complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The HRTF adjustment process is segmented by identifying and manipulating specific frequency regions (pinna notches) independently rather than adjusting the entire HRTF spectrum. This segmentation allows targeted modification of vertical localization cues while preserving other auditory information, reducing adjustment complexity and distortion risk.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention applies local quality by focusing adjustments on specific frequency regions corresponding to pinna notches rather than uniformly adjusting all frequencies. This localized approach targets the specific spectral features that encode vertical position information, improving precision while minimizing overall complexity and avoiding unnecessary modifications to other frequency regions.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If personalized HRTF adjustments are made for each user to account for ear shape variations, then accuracy of vertical displacement simulation improves, but processing requirements and computational complexity increase

Engineering Contradiction:

Improvevertical displacement simulation accuracyVSAvoidprocessing efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The invention applies universality by using a standardized set of frequency region adjustments based on typical pinna notch characteristics that can be applied across different users. Rather than creating fully personalized HRTF adjustments for each individual, the method uses universal frequency region identification and manipulation strategies that work effectively for most users, reducing processing requirements while maintaining acceptable accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention changes parameters by identifying specific frequency regions (pinna notches) and applying targeted amplitude adjustments to those regions. This parameter-focused approach modifies only the relevant spectral characteristics needed for vertical localization without requiring comprehensive personalization of all HRTF parameters, thereby improving processing efficiency while maintaining simulation accuracy.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If frequency region amplitude adjustments are applied to simulate vertical displacement, then perceived elevation accuracy improves, but the risk of distorting the overall sound increases

Engineering Contradiction:

Improveperceived elevation accuracyVSAvoidsound distortion

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention applies partial action by adjusting only the specific frequency regions corresponding to pinna notches rather than modifying the entire frequency spectrum. This partial adjustment targets the critical frequency regions that encode vertical position information while leaving other frequency regions unchanged, thereby improving elevation accuracy without introducing unnecessary distortion to the overall sound.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The invention uses copying by preserving the original HRTF characteristics in frequency regions outside the targeted pinna notch areas. The unadjusted frequency regions serve as a copy of the original sound characteristics, maintaining fidelity and preventing distortion while the adjusted frequency regions provide the necessary vertical localization cues.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS12549921B2Methods and systems for simulating perception of a sound source

Publication Date: 2026.02.10 SONY COMP ENTERTAINMENT EURO LTD

AI summary

An audio personalisation method for simulating perception of a vertical displacement of a sound source, the method comprising the steps of: obtaining an input head related transfer function, HRTF, associated with a user; determining an intended vertical displacement for the sound source; selecting at least one frequency region in the input HRTF; and adjusting the amplitude of the selected frequency region(s) to simulate the intended vertical displacement for the sound source. This provides improvements to the generation and/or manipulation of HRTFs to allow adjustment of the perceived location of a sound source.