Perceived spaciousness scales with playback level because faint reflected sounds must be audible

Evidence

Spaciousness is dependent on playback sound level because the illusions require that low-level reflected sounds be audible. The more of these sounds that are heard, the greater is the spatial impression. In live concert hall performances, profound spaciousness is most experienced in loud passages. In reproduction it is more apparent at high sound levels and in the absence of loud background masking noises. In car audio, spaciousness is best experienced when parked. It significantly reduces as background noise increases with speed, which is one motivation for premium systems to upmix to multichannel, and to adjust sound level as a function of speed. — Toole, Floyd E, Sound reproduction- the acoustics and…, 374

Categorization

• ADDENDUM: Supports the framework in the trees article’s sibling themes by grounding spatial-imagery perception in audibility thresholds; also connects to car-audio upmixing as level-compensated multichannel practice.
• XREF: connects to: Children’s voices raise perceived crowding in sparse parks but relieve it in crowded ones — Almo Farina, Soundscape Ecology: Principles,…, 2305