3-D Sound and Spatial Audio. MUS_TECH 348. Environmental Acoustics and Perception. Subjective Preferences for Concert Halls. Schroeder’s work led to the understanding of the importance of side reflections and the decorrelation of the late field.
Schroeder’s work led to the understanding of the importance of side reflections and the decorrelation of the late field.
There are four significant dimensions in preference judgments. Two are represented here.
Numbers represent listeners and Capital letters are concert halls. Halls H, K and J are most preferred.
“Initial reverberation time” (T) is highly correlated to preference D1 and “definition” is negatively correlated. These are somewhat inversely related. Other factors with negative correlation are: “width of hall” (W) and “interaural coherence” (C).
People appear to prefer longer reverberation times, narrower halls and low interaural coherence.
Rasch and Plomp discuss how spaciousness, a desirable property, is captured in the ratio of indirect to direct sound.
Key questions arise about the relative importance of indirect sound coming from the side walls, ceiling and rear wall.
Rasch and Plomp report how synthetic indirect sound can be manipulated for experimental purposes.
Ceiling, rear wall and floor reflections
Side wall reflections
The direction from which indirect sound arrives has a strong impact on the similarity of the energy arriving at the ears.
The subject quality of “spaciousness”:
Spaciousness depends on interaural incoherence.
Concert hall design should attempt to create interaural incoherence in the indirect sound.
1D and 2D Quadradic
Residue Diffusers (QRDs) invented by Schroeder.
Altar / Stage / Screen
Spiritual / Emotional