Musicians need acoustic reflections within 20 ms for comfortable ensemble playing

Evidence

There is evidence to show that, in order to maintain good ensemble comfortably, the musicians should receive the sound from other musicians within about 20 ms of the sound being produced. This means that ideally there should be a reflecting or diffusing surface within 10 ms (3.44 m or 11.5 ft) of the performer; the time is divided by 2 to allow for sound going to the reflecting surface and back. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1939

Categorization

• XREF: Connects to the reader’s broader psychoacoustics project on listening and silence — early reflection timing is core physical acoustics rather than subjective listening, but the 20 ms/50 ms boundary directly parallels echo perception thresholds. — connects to: Early reflections from nearby surfaces give performers essential auditory feedback; Stage design must balance sending sound to audience and reflecting it back to performers; Ensemble playing depends on performers receiving reflections within roughly 20 milliseconds (+1 more)
• DEFINE: Defines acoustic foldback: the reflected sound performers receive from other musicians that enables ensemble coordination.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1939

Broader Connections

• Ensemble playing depends on performers receiving reflections within roughly 20 milliseconds #corroborates (1.00)
• Late early reflections can ruin performers’ ability to hear each other and maintain ensemble #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1942