Headphone Spatial Audio Timbre Equalization Before HRTF Playback
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Solution Overview
Problem
Existing virtual spatial sound playback technologies using head-related transfer functions (HRTF) cause spectral distortion in the mid and high-frequency sections of sound signals, leading to changes in timbre during 3D spatial playback.
Innovation Solution
Implement a timbre equalization function to process the original sound signal based on spatial orientation information, followed by HRTF filtering, using crossover points and gain factors to minimize timbre changes while maintaining spatial positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If HRTF function is used to produce 3D spatial playback effects, then spatial positioning accuracy is improved, but timbre changes due to spectral distortion in mid and high-frequency sections
Solution Approach 1:
The patent applies timbre equalization preprocessing to the original sound signal before HRTF spatial processing. By pre-adjusting the frequency response curve to compensate for expected spectral distortion, the timbre is preserved while spatial positioning accuracy is maintained through subsequent HRTF processing.
Solution Approach 2:
The patent dynamically adjusts equalization parameters (gain factors, crossover frequencies) based on the spatial orientation angles (azimuth and elevation) of the virtual sound source. This allows the timbre compensation to adapt to different spatial positions, maintaining both spatial accuracy and timbre consistency across various playback scenarios.
2Adaptability or versatility
If HRTF function changes frequency response curve to convey 3D spatial positioning cues, then spatial auditory effect is improved, but spectral distortion occurs especially in mid and high-frequency sections
Solution Approach 1:
The system pre-processes the sound signal with timbre equalization before spatial encoding. The frequency response curve is adjusted in advance to counteract the spectral distortion that will be introduced by HRTF processing, ensuring that the final output maintains both spatial effects and spectral fidelity.
Solution Approach 2:
The patent converts the harmful spectral distortion into a benefit by using it as a reference for designing the equalization filter. The known distortion characteristics of HRTF are utilized to create compensatory equalization curves, turning the distortion problem into a solvable engineering challenge with predictable solutions.
3Object-generated harmful factors
If timbre equalization is applied to reduce spectral distortion, then timbre consistency is improved, but device complexity increases due to additional processing stages
Solution Approach 1:
The patent implements a parametric equalization model with adjustable gain factors and crossover frequencies that can be configured based on the desired spatial orientation. This allows flexible timbre control without requiring complex fixed-filter designs, simplifying the overall system while maintaining timbre consistency.
Solution Approach 2:
The timbre equalization module serves multiple functions: it compensates for spectral distortion, adapts to different spatial orientations, and can be adjusted for various listening preferences. This multi-functionality reduces the need for separate processing stages, thereby managing complexity while achieving timbre consistency.
Data Source
AI summary
A method of headphone virtual spatial sound playback, which includes: performing filtering on an input original sound signal A0 through a timbre equalization function C based on spatial orientation information of an intended virtual sound source, to obtain an equalized sound signal AC; then filtering the equalized sound signal AC through an HRTF function, and outputting a left ear sound signal AL and a right ear sound signal AR; wherein, the spatial orientation information of the intended virtual sound source comprises a horizontal orientation angle θ and a vertical orientation angle φ; the relationship between the equalized sound signal AC and the original sound signal A0 is expressed as: AC=A0C. The disclosure enables an original sound signal to produce spatial auditory effect through HRTF function filtering, performs timbre equalization on the original sound signal and reduces timbre change in virtual space sound playback, and does not affect or change the spatial positioning performance of the original HRTF.