Lateral diffuse reflections are required for listener enjoyment

Evidence

The second factor that has been found to be important for the listener is the presence of dense diffuse reflections from the side walls of a concert hall, called lateral reflections, as shown in Figure 6.24. The effect of these is to envelop or bathe the listener in sound, and this has been found to be necessary for the listener to experience maximum enjoyment from the sound. It is important that these reflections be diffuse, as specular reflections will result in disturbing comb filter effects, as discussed in Chapter 1, and distracting images of the sound sources in unwanted and unusual directions. Providing diffuse reflections is thus important, and this has been recognized for some time. Traditionally, plaster mouldings, niches, and other decorative surface irregularities have been used to provide diffusion in an ad hoc manner. More recently, diffusion structures based on patterns of wells whose depths are formally defined by an appropriate mathematical sequence have been proposed and used. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1927

The second factor that has been found to be important for the listener is the presence of dense diffuse reflections from the side walls of a concert hall, called lateral reflections, as shown in Figure 6.24. The effect of these is to envelop or bathe the listener in sound, and this has been found to be necessary for the listener to experience maximum enjoyment from the sound. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1927

Categorization

• XREF: Comb filter effects were defined in Chapter 1; connects to the reader’s understanding of how specular reflections cause interference. — connects to: Lateral sounds drive spatial perception more than frontal or rear sounds; Wide-dispersion speakers plus room reflections create listener envelopment.; Diffuse surfaces scatter sound hemispherically rather than mirror-like — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2318 (+3 more)
• FICTION: The shift from ad-hoc plaster ornaments to mathematically-derived diffusion wells could seed a story about tradition and engineered perfection in architecture.
• DEFINE: Introduces lateral reflections and the envelopment/sense-of-space concept central to concert-hall psychoacoustics.
• corroborated: 3 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1927

Broader Connections

• Wide-dispersion speakers plus room reflections create listener envelopment. #expands (0.80)
• Diffuse surfaces scatter sound hemispherically rather than mirror-like #expands (0.75) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2318
• Engineered diffusers attenuate the specular reflection toward the listener by up to 20 dB #corroborates (0.72)