Reverberator pre-delay controls perceived source distance independently of loudness ratio

Evidence

Added to this, audio engineers utilize another method to control distance perception using reverberators, wherein the auditory events caused by at least some types of sounds (typically voice) can be moved closer or farther away by changing the pre-delay parameter. Reverberators are audio effects, which, in principle, convolve a monophonic sound signal with the room response. The pre-delay parameter controls the temporal gap between the direct sound and the rest of the response. Shortening the pre-delay moves the perceived source farther away and making it longer brings it closer. Physically this makes sense, since a long gap would correspond to a situation where the direct path is much shorter than the reflected path, which can only happen if the source is close. This is different from the direct-to-reverberant ratio cue, since the ratio does not change. A very similar effect has been found in virtual reality simulations. When the first reflections are moved temporally in an impulse response without changing the properties of the late reverberation, the perceived distance changes systematically (Pellegrini, 2002). — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1527

Added to this, audio engineers utilize another method to control distance perception using reverberators, wherein the auditory events caused by at least some types of sounds (typically voice) can be moved closer or farther away by changing the pre-delay parameter. Reverberators are audio effects, which, in principle, convolve a monophonic sound signal with the room response. The pre-delay parameter controls the temporal gap between the direct sound and the rest of the response. Shortening the pre-delay moves the perceived source farther away and making it longer brings it closer. Physically this makes sense, since a long gap would correspond to a situation where the direct path is much shorter than the reflected path, which can only happen if the source is close. This is different from the direct-to-reverberant ratio cue, since the ratio does not change. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1527

Categorization

• XREF: Connects directly to the reader’s stated purpose on acoustic communication applications; a concrete tool audio engineers use to shape how listeners perceive spatial relations — parallels the pre-delay discussion in sound design for VR and film. — connects to: Relative loudness change provides the key auditory cue for source distance; Direct sound determines localization, loudness, and perceived spectrum quality — , Toole, Floyd E - Sound reproduction-…, 1546; The gap between direct sound and reverberation encodes the perceived size of a space — David Howard, Jamie Angus, coustics and Psychoacoustics, 1776 (+2 more)
• SEED: A technical explainer angle: the reason a long gap between direct and reflected sound must mean the source was close — how reverbs fool the auditory system via physics.
• ADDENDUM: Shows causality in the same family as how reverberation and reflections encode distance; complements the earlier chapters that covered direct-to-reverberant ratios.
• corroborated: 4 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1527

Broader Connections

• The gap between direct sound and reverberation encodes the perceived size of a space #qualifies (0.85) — David Howard, Jamie Angus, coustics and Psychoacoustics, 1776