Speaker Array Virtual Surround Sound Rendering
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Solution Overview
Problem
Existing virtual speaker sound systems that use few speakers struggle with narrow sweet spots and off-axis sound distortion when listeners move their heads, due to limitations in spatial enhancement techniques and crosstalk canceller methods.
Innovation Solution
A digital signal processor employing first-order head-related filters, upmixing matrices, and delay lines to generate early reflections, which are used in a speaker array to create robust virtual surround sound with reduced off-axis coloration by combining audio signals from a stereo or surround sound system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spatial enhancement techniques are used with few speakers arranged in front of the listener, then surround sound can be rendered without rear speakers, but the sweet spot becomes very narrow and does not allow larger head movements
Solution Approach 1:
The patent employs dynamic head-related transfer functions (HRTFs) that adapt to the listener's head position and orientation. The system dynamically adjusts the spatial enhancement parameters based on head movement detection, allowing the narrow sweet spot issue to be resolved by making the sound field adaptive rather than static.
Solution Approach 2:
The system changes the parameters of the spatial enhancement filters based on the listener's head position. By modifying the filter coefficients dynamically according to head orientation, the system maintains accurate sound imaging across a wider range of head positions, effectively expanding the sweet spot.
2Measurement precision
If high order inverse filter matrices are used to generate exact ear signals, then accurate sound rendering is achieved, but sound quality degrades off axis where the listener's head is not at the exact intended position
Solution Approach 1:
Instead of using high order inverse filter matrices that attempt to perfectly cancel crosstalk, the patent employs partial cancellation with lower order filters. This partial action approach reduces computational complexity while maintaining sufficient off-axis sound quality, avoiding the over-engineering that leads to degradation.
Solution Approach 2:
The system uses simpler, lower order filter matrices that are computationally cheaper and more robust to position variations. Rather than investing in complex high order matrices that are sensitive to positioning errors, the patent employs simpler filters that are more tolerant of off-axis listening positions.
3Productivity
If conventional crosstalk canceller circuits are used prior to crossover filters, then some surround sound rendering is achieved, but the crosstalk canceller filters are not optimized for either of the transducer pairs resulting in limited success
Solution Approach 1:
The patent applies different crosstalk cancellation strategies for different transducer pairs. Instead of using a single conventional crosstalk canceller for all speakers, the system optimizes the cancellation filters specifically for each transducer pair's positioning and acoustic characteristics, improving overall rendering accuracy.
Solution Approach 2:
The system dynamically adjusts the crosstalk cancellation parameters for each transducer pair based on the listener's position and the specific speaker configuration. This dynamic optimization allows the crosstalk canceller to adapt to different listening scenarios rather than using fixed parameters.
Data Source
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AI summary
An approach and device for generation of virtual surround sound with a two-way approach that employs a first order head-related models have been used that resemble interaural time difference localization and inter-aural level difference localization cues in the respective frequency bands while avoiding phantom imaging and excessive coloration.