Interaural Time Delay Shifting to Reduce Binaural Comb Filtering
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Solution Overview
Problem
Undesirable comb filtering effects occur when rendering binaural sound simulated as coming from multiple virtual speakers, with the ipsilateral ear being more sensitive to these artifacts.
Innovation Solution
Adjust the interaural time delays (ITDs) for audio streams emitted by virtual sound sources to redistribute delays between ipsilateral and contralateral ears, ensuring a constant ITD period while minimizing differences in delay distribution, thereby reducing comb filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If binaural sound is simulated as coming from multiple virtual speakers, then spatial audio realism is improved, but comb filtering artifacts are generated in the ipsilateral ear
Solution Approach 1:
The patent applies different delay treatments to different ears: the ipsilateral ear receives adjusted delays to minimize comb filtering, while the contralateral ear maintains the original ITD characteristics. This local differentiation resolves the contradiction by protecting the sensitive ipsilateral ear while preserving spatial realism for the contralateral ear.
Solution Approach 2:
The patent modifies the delay parameters specifically for the ipsilateral ear by calculating adjusted delays that maintain the ITD period while redistributing the delay distribution. This parameter change eliminates comb filtering artifacts in the ipsilateral ear while maintaining overall spatial audio realism.
2Reliability
If ITD delays are adjusted to reduce comb filtering in the ipsilateral ear, then sound quality is improved, but the original ITD delay distribution is altered
Solution Approach 1:
The patent segments the ITD delay into two components: the ITD period (which is preserved) and the delay distribution (which is adjusted). By separating these aspects, the patent maintains the fundamental ITD characteristics while optimizing the delay distribution to reduce comb filtering, thus improving sound quality without completely altering the ITD structure.
Solution Approach 2:
The patent selectively changes only the necessary delay parameters for the ipsilateral ear while maintaining the ITD period constant. This controlled parameter change improves sound quality by reducing comb filtering while preserving the essential ITD delay distribution characteristics needed for spatial perception.
Data Source
AI summary
To reduce comb filtering in the ipsilateral when rendering binaural audio from plural virtual speakers on, for example, headphones, the ipsilateral delays of the ITDs of the respective speakers can be reduced to zero and the contralateral delays increased to maintain the same temporal length of the ITDs, shifting the delays to the less important contralateral ear.