Delayed identical sounds fuse into one source until a 30-40 ms echo threshold

Evidence

When τ is zero, the listener perceives a single sound event in front, and when τ is increased to about 1 ms, the single spatial auditory event migrates towards the lead sound event. The spatial perception remains the same until the onset of the echo threshold, which occurs for values of τ of about 30–40 ms, depending on the signal. Only after this threshold is crossed does the lag sound event create an additive, spatially separated auditory event. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1500 (#corroborates, via linked claim)

The sensation of a distinct echo begins around a 0.1 s (100 ms) delay and longer. However, if a tone were played for many seconds, the echo would no longer be perceived as distinct. If a monaural recording is made under these circumstances at a single point and played back, a listener would perceive the tone as affected by the enhancement and suppression combs, spaced by 10 Hz. — Eric J. Heller, Why You Hear What You Hear- An…, 2551 (#complicates, via linked claim)

Categorization

• XREF: connects to: Two identical sounds within 30–40 ms are fused into one located auditory event. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1500; Delayed identical sounds merge spatially until delays exceed 30-40 ms — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1500; Echoes arise only when reflected sound exceeds a 30-millisecond delay (+3 more)

Broader Connections

• Delayed identical sounds merge spatially until delays exceed 30-40 ms #corroborates (0.97) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1500
• A 30-40 ms delay separates fusion from echo in the precedence effect #expands (0.95)
• Delays under 100 ms are heard as timbre change rather than distinct echo #complicates (0.74) — Eric J. Heller, Why You Hear What You Hear- An…, 2551