Deep broadband diffusers can create a 30 dB immediate reflection drop
Evidence
Whatever the expectations were, the reality is interesting. An immediate 30 dB drop is very like an anechoic space. The 0.3 s decay time (RT) that follows implies that the energy has been very uniformly dispersed in time and space. The high density of reflections from the diffusing surfaces that start almost immediately is the unique feature. The creators called it “Ambechoic”—an ambient anechoic space. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1430
Categorization
- DEFINE: Introduces the ‘Ambechoic’ concept — a useful term for describing a room that combines anechoic early drop with dense dispersed reflections.
- XREF: Connects to the craft of room design: the measured ETC profile (30 dB early drop, 0.3 s RT) is a concrete design target a reader modeling room acoustics could replicate. — connects to: Diffusers mainly attenuate specific reflections rather than create diffuse fields — Toole, Floyd E, Sound reproduction- the acoustics and…, 1257; Engineered diffusers attenuate the specular reflection toward the listener by up to 20 dB
- corroborated: 2 independent passages support this claim — Toole, Floyd E, Sound reproduction- the acoustics and…, 1430