Binaural Audio Rendering for In-Head Sound Positioning
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Solution Overview
Problem
Existing binaural sound synthesis methods fail to accurately simulate sound sources close to the listener, leading to undesirable audio signals and discomfort due to prominent head shadowing effects, especially when the sound source is between the listener's ears.
Innovation Solution
A method and device for rendering binaural audio signals that filter sound programs to produce low-frequency and high-frequency portions, panning the high-frequency portions according to the sound location between the earpieces to create an in-head audio experience, while maintaining a constant low-frequency portion to prevent occlusion feelings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If binaural filters are used to simulate sound sources close to the listener, then the sound position accuracy is improved, but head shadowing effects become prominent causing discomfort
Solution Approach 1:
The patent divides the sound signal into multiple frequency bands (low-frequency and high-frequency portions) and processes each band differently. Low-frequency signals are applied to both ears equally while high-frequency signals are panned according to the sound source position, preventing head shadowing effects while maintaining spatial accuracy.
Solution Approach 2:
Different frequency components are treated with different spatial processing strategies. Low-frequency components are distributed uniformly to both ears, while high-frequency components are directionally panned, creating locally optimized quality for each frequency range to avoid discomfort.
2Measurement precision
If sound pressure levels are increased at the ipsilateral ear for near-field sounds, then the sound intensity accuracy is improved, but the contralateral ear experiences occlusion and discomfort
Solution Approach 1:
The patent segments the audio signal by frequency, applying different intensity strategies to low and high frequencies. Low-frequency signals maintain constant intensity at both ears, while high-frequency signals receive directional panning, thereby achieving intensity accuracy without causing occlusion.
Solution Approach 2:
The patent converts the potentially harmful head shadowing effect into a beneficial spatial cue by applying it only to high-frequency signals. This allows the natural ILD effect to provide accurate spatial information while the low-frequency content maintains comfort by preventing occlusion.
Data Source
AI summary
In a device or method for rendering a sound program for headphones, a location is received for placing the sound program with respect to first and second ear pieces. If the location is between the first ear piece and the second ear piece, the sound program is filtered to produce low-frequency and high-frequency portions. The high-frequency portion is panned according to the location to produce first and second high-frequency signals. The low-frequency portion and the first high-frequency signal are combined to produce a first headphone driver signal to drive the first ear piece. A second headphone driver signal is similarly produced. The sound program may be a stereo sound program. The device or method may also provide for a location that is between the first ear piece and a near-field boundary. Other aspects are also described.