Early reflected sound localizes sources while late sound becomes directionless

Evidence

Consider a loud note played from stage. Direct sound reaches the audience first, followed shortly by sound that has bounced once off a wall or ceiling. This early sound is clearly directional, and we use it to determine the location of the source. Sound arriving later from the same note has traveled farther, bouncing many times off back and side walls and ceilings and diffracting off statuary, balconies, and so on, and is nearly omnidirectional. In a rather reverberant hall with a T60 of 3 seconds, the sound will have traveled a kilometer before its last remnants reach the audience’s ears. The late sound has spread uniformly throughout the space and is moreover propagating every which way, equally. — Eric J. Heller, Why You Hear What You Hear- An…, 2471

Categorization

• DEFINE: Distinguishes directional early reflections from omnidirectional late reverberation — the mechanism behind source localization in rooms.
• SHARE: The kilometer-traveled stat gives a vivid scale for what T60 means in a real hall.
• ADDENDUM: Worth mentioning in ‘Grafting & Growth’ context only as comparison — this is really a sound-piece, so more naturally a parallel to the silences reading.
• corroborated: 2 independent passages support this claim — Eric J. Heller, Why You Hear What You Hear- An…, 2471
• XREF: connects to: The first arriving sound wave dominates perceived localization regardless of level — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1564; Sound is localized to the first arriving acoustic source despite delayed reinforcement; Room reverberation barely affects early reflection audibility but strongly elevates late-reflection thresholds — Toole, Floyd E, Sound reproduction- the acoustics and…, 630 (+7 more)

Broader Connections

• Sound is localized to the first arriving acoustic source despite delayed reinforcement #corroborates (0.92)
• Late-arriving reflections within the fusion zone are audible but merge into one directional image #qualifies (0.85)
• Room reverberation barely affects early reflection audibility but strongly elevates late-reflection thresholds #expands (0.80) — Toole, Floyd E, Sound reproduction- the acoustics and…, 630
• The sound arriving first dominates perceived direction beyond 673 microseconds of delay #qualifies (0.80)
• The precedence effect suppresses spatial identity of reflections, not their audibility #expands (0.78) — , Toole, Floyd E - Sound reproduction-…, 840