The 30 ms fusion limit applies only to equal-level speech in hemi-anechoic space

Evidence

In the field of architectural acoustics it has long been recognized that early reflections improve speech intelligibility. For this to happen, they must arrive within an “integration interval” within which there is an effective amplification of the direct sound—it is perceived to be louder. For speech, single reflections at the same level as the direct sound contribute usefully to the effective sound level, and thereby the intelligibility, up to about a 30 ms delay. For delayed sounds 5 dB lower than the direct sound, the integration interval is about 40 ms. These intervals embrace all consequential early reflections in domestic rooms or control rooms, although in larger rooms longer delays can be problematic (Lochner and Burger, 1958). — , Toole, Floyd E - Sound reproduction-…, 824 (#qualifies, via linked claim)

Categorization

• XREF: connects to: Early reflections within 30-40 ms improve speech intelligibility — , Toole, Floyd E - Sound reproduction-…, 824; The precedence-effect fusion interval in real rooms far exceeds laboratory values

Broader Connections

• Early reflections within 30-40 ms improve speech intelligibility #qualifies (0.75) — , Toole, Floyd E - Sound reproduction-…, 824