Spatialized Audio Equalization for Direction-Dependent Tonal Coloration
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Solution Overview
Problem
Spatializing multichannel audio signals often introduces undesired tonal coloration that changes with the user's perception of sound direction, particularly in binaural listening devices, making it difficult to achieve optimal sound quality and user comfort.
Innovation Solution
A method involving equalizers that compensate for undesired coloration by determining equalizer coefficients based on head-related filters' transfer functions in a mono-source scenario, applied to both lateral spatializers to process spatialized audio signals for each ear, ensuring alignment with predefined target transfer functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spatializing methods are applied to multichannel audio signals to provide spatial cues for binaural listening, then the perception of sound sources positioned far from the user's head is improved, but undesired tonal coloration is introduced that changes with sound direction perception
Solution Approach 1:
The patent introduces an intermediary processing stage between spatialization and audio output: equalizers are applied to the spatialized audio signals to compensate for tonal coloration. These equalizers act as mediators that correct the frequency response distortions introduced by spatializing filters, allowing both spatial perception and tonal accuracy to be maintained simultaneously
Solution Approach 2:
The patent dynamically adjusts equalizer parameters based on the spatial position of sound sources. As sound sources move across different spatial positions, the equalizer parameters are changed to compensate for the direction-dependent tonal coloration, maintaining flat frequency response across all spatial positions while preserving the spatial perception effect
2Adaptability or versatility
If head-related filters are used to emulate acoustic paths from virtual loudspeakers to user's ears, then spatial positioning of sound sources is achieved, but frequency response distortion and tonal coloration occur
Solution Approach 1:
The patent implements a feedback mechanism where the tonal coloration introduced by head-related filters is measured and characterized, then used to design compensating equalizers. The equalizer parameters are determined based on the inverse of the spatializing filter's frequency response, creating a feedback loop that cancels out the distortion and maintains accurate frequency response while preserving spatial positioning
3Measurement precision
If dummy-head recording is used to provide spatial cues optimized for binaural listening, then spatial perception is improved for users with similar head sizes, but the method is not practical for providing multichannel audio signals suitable for quality reproduction to a large variety of users
Solution Approach 1:
The patent creates a universal spatialization system that works for all users regardless of head size or outer ear shape. Instead of requiring personalized dummy-head recordings for each user, the system uses head-related filters combined with compensating equalizers that correct for individual variations, making the spatialization technology universally applicable while maintaining high spatial perception quality for all users
Data Source
AI summary
A method for processing an audio signal comprising a first and second spatialized audio signal, wherein the first audio signal has a first lateral spatializer of a multichannel audio spatializer, the second spatialized audio signal (R1) a second lateral spatializer of the multichannel audio spatializer, and the first and second spatialized audio signals differs from the each other. Also disclosed is a first equalizer transfer function receiving and filtering the first spatialized audio signal from first set of equalizer coefficients to provide a first equalized audio signal and second equalizer transfer function receiving and filtering the second spatialized audio signal.