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Limitations of reverberation time in non-diffuse conditions

Jack Harvie-Clark had two papers at Euronoise 2012, the first looking at reverberation time in school halls and the other concerning surprisingly high sound insulation test results between classrooms.

Reverberation Times in School Halls: Measurements and Modeling
Jack Harvie-Clark, Nicholas Dobinson, David Moore, Peter Ward, Richard Hinton
Jack discussed how reverberation time is dominated by the grazing sound field in empty sports and assembly halls. The measurements illustrated the large deviation from Sabine conditions particularly between 250-2000Hz, results that were also difficult to reproduce with ray-tracing modelling, and would be difficult to predict with any certainty. As the reverberation time measurement looks at the tail of the impulse response, measures such as C50, speech clarity and G, sound strength may more closely represent the acoustic qualities that we need and are interested in.
Acoustic Response in Non-Diffuse Rooms
Jack Harvie-Clark, Nicholas Dobinson, Richard Hinton
In his other paper, Jack discussed how field sound test measurements between classrooms can sometimes exceed laboratory values. A possible cause for the overestimation of sound insulation arises again because the reverberation time does not represent the effect of the room in supporting noise levels. Sound strength, G, is a measure of the sound level in a room due to a sound source. Measurements show that in classroom type rooms, more correct and consistent values of sound insulation may be measured by using G to account for receiving room conditions.

Educational Environments 178 Research 163

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