Engineered diffusers attenuate the specular reflection toward the listener by up to 20 dB

Evidence

Figure 12.27 shows that incoming sound from a loudspeaker at 30° incidence is redirected almost uniformly over a 180° angular range. The flat surface reflects the bulk of the energy towards the listener at the symmetrical angle. In this demonstration the effective attenuation of the reflected sound is an impressive 20 dB. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1394

Categorization

Category: Factual Claims

• XREF: Connects to earlier chapters on reflection management and ETC interpretation; also relevant to side-wall reflection control in listening room design.

Related

• Diffusers mainly attenuate specific reflections rather than create diffuse fields (similarity 0.87)
• Lateral diffuse reflections are required for listener enjoyment (similarity 0.86)
• Ceiling-reflected diffuse sound cannot substitute for real side-wall reflections (similarity 0.86)
• Early lateral reflections are attenuated by loudspeaker directivity, not harmful. (similarity 0.84)
• A resistive absorber behind the listener solves reflective-wall problems where diffusers fail (similarity 0.84)
• Deep broadband diffusers can create a 30 dB immediate reflection drop (similarity 0.83)
• Diffusing surfaces may not reduce perceived reflection loudness as expected (similarity 0.83)
• Reflection and diffraction of sound both depend on object size relative to wavelength (similarity 0.83)
• Early side-wall reflections range neutral to beneficial with well-designed loudspeakers (similarity 0.83)
• Diffusor effectiveness in small listening rooms lacks subjective validation (similarity 0.83)
• Diffuse surfaces prevent sound focusing away from the optimum listening position (similarity 0.83)
• Diffuse wall reflections are temporally spread and lower in level than specular ones (similarity 0.82)
• Real reflections are attenuated enough to tame comb filtering drastically (similarity 0.82)
• Removing conflicting reflections improves perception of low-level audio detail (similarity 0.82)
• Real-room reflections are attenuated and delayed, not equal-level and immediate. (similarity 0.82)

Broader Connections

• Redirecting reflections creates uneven hot spots while absorption shortens reverberation #contradicts (0.78) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2291