Reverberation in Rectangular Long Enclosures with Geometrically Reflecting Boundaries

In this paper theoretical formulae for calculating the reverberation in rectangular long enclosures with geometrically reflecting boundaries are derived by applying the image source model. The theory has been validated by the measurements in a corridor. Computations with these formulae show that in long enclosures: with the increase of source-receiver distance, the reverberation time increases sharply to a maximum and then decreases slightly; the decay curves are convex, especially in the near field; with air absorption, the decay curves are more linear; with the same cross-sectional form, the reverberation time increases with the increase of cross-sectional area, and this increase is more significant for a longer source-receiver distance; with the same cross-sectional area, the reverberation time is the longest when the section is square; highly reflective end walls could increase the reverberation significantly; the reverberation could be adjusted by using a directional source and; the reverberation of multiple sources is longer than that caused by the nearest source alone. An auditorium-like enclosure is also analysed.