Strong diffuse reflections can make a room sound anechoic while still reverberant.

Evidence

Figure 7.33 shows one of the few examples of such a room. The experience of this room is that one is unaware of sound reflection from the walls: it sounds almost anechoic, yet it has reverberation. Stereo and multichannel material played in this room has images that are stable over a wide listening area, as predicted by theory. The room is also good for recording in, as the high level of diffuse reflections and the acoustic mixing it engenders, as shown in Figure 7.30, help integrate the sound emitted by acoustic instruments. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2332

Categorization

• XREF: Connects to the book’s earlier treatment of diffuse sound fields and reverberation, and to listening experiences where a space seems ‘dead’ despite measurable reverb. — connects to: Diffuse reflections create a larger, forgiving sweet spot in listening rooms — David Howard, Jamie Angus, coustics and Psychoacoustics, 2310
• QUESTION: What architectural and surface parameters produce a room whose reflections are both strong and perceptually undetectable as discrete echoes?