Spatial Resolution of Late Reverberation in Virtual Acoustic Environments.
Christoph Kirsch, Josef Poppitz, Torben Wendt and 2 others
PMID 34935544WHAT IT FOUND
Virtual acoustic environments need only 12 sound directions to realistically simulate late reverberation for speech, matching human perception and technical accuracy.
Fewer directions fail with transient sounds or head movement, but 12 is sufficient for most hearing aid research applications.
Key findings
01For isotropic late reverberation, 12 virtual reverberation sources are sufficient to perceptually approximate a spherically isotropic sound field with transient stimuli, while even 6 may suffice for speech.
02For anisotropic late reverberation, 12 to 24 virtual reverberation sources appear sufficient to render the late reverberation, with 6 sources being clearly distinguishable from the reference for most stimuli.
03Technical evaluation showed that 12 or more virtual reverberation sources allow for accurate reproduction of sound field coherence at ear distance up to at least 1.5 kHz, which aligns with the frequency limit for sensitivity to interaural time differences.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used a specific 86-channel loudspeaker array with an inhomogeneous distribution, which may not represent all laboratory setups. The technical evaluation focused primarily on coherence, acknowledging that other binaural cues also contribute to spatial impression. Listeners had normal hearing, so the results may not directly generalize to how hearing-impaired patients perceive these virtual environments. The study did not test the relative orientation of the virtual sources and the loudspeaker array, keeping that parameter fixed.
Declared interests
The authors declared no potential conflicts of interest. The work was funded by the Deutsche Forschungsgemeinschaft (German Research Foundation).
The easy way to misread this
Do not assume that 6 virtual reverberation sources are adequate for all applications. While 6 sources may suffice for static speech tests, the study found that 12 to 24 sources are necessary to accurately render transient sounds and to maintain spatial fidelity when a listener moves their head.