Efficiency factors characterizing sound reflection properties of a room ceiling
نویسنده
چکیده
The shape of a room ceiling influences acoustics of the room dramatically. Bad shape causes many acoustic defects like sound focusing, high delays, lack of reflections, whereas good shape provides useful support of the direct sound and as a result increases loudness, improves speech and music intelligibility. Many books give recommendations on the ceiling geometry, which has to be designed to reflect sound to the rear of the room, or to diffuse it throughout the room. But any quantitative parameters for characterizing efficiency of sound reflection from the ceiling are not applied in practice. It seems that it would be useful to specify the room ceiling by any parameters describing its reflection properties. For this purpose two efficiency factors in framework of geometrical acoustics are proposed in presented paper. First factor is a ratio of the sound energy reflected from the ceiling towards seats to the sound energy incident to the ceiling. At the best, this ratio equals 1, but not always maximal ratio corresponds with good ceiling shape. For this reason second factor is also used, it is a ratio of the sound energy reflected from the ceiling towards seats to sound energy radiated by a source into the room. Maximal value of second factor is defined by a ratio of the room height to the room length. The room with a balcony requires refinement of efficiency factors definition. Possible way is to separate the sound energy reflected by the ceiling into the energy reflected towards the main floor and the energy reflected towards the balcony. Proposed efficiency factors are analysed for four classic concert halls with excellent acoustics. It provides preliminary values of the factors suitable for evaluation of acoustic properties of the room ceiling.
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ورودعنوان ژورنال:
- Proc. Meetings on Acoustics
دوره 28 شماره
صفحات -
تاریخ انتشار 2016