Ray statistics in reverberation.
01 January 1988
Architects calculate the reverberation time of a room from one of four simple approximate formulas (Sabine, Eyring, Millington, Kuttruff). Just the common assumptions, that all four formulas share, are used here to derive a new approximate reverberation time by a queueing theory argument. The new approximation is exact for diffuse spheres but is inconvenient to use in general. The standard simpler formulas are obtained as approximations to the new one by making further assumptions. To compare these formulas, they are applied to diffusely-reflecting ellipsoidal rooms. Kuttruff's approximation requires the least drastic extra assumptions and is usually closest to the new one. However the common assumptions, which the new approximation uses, can be so far from true that even Kuttruff's formula is inaccurate in some examples.