Reduction of acoustic annoyance in school dining halls.

The sound levels in dbA and the reverberation times in sec were measured in 18 school dining areas in and around Rennes. Of these, 12 had had acoustic treatment, 6 had not. The range of levels in all schools exceeded those recommended in the literature for the avoidance of noise-induced fatigue, while the reverberation times were acceptable (less than 0.8 sec) only in those spaces acoustically treated. There was a clear relation between sound level and reverberation times, but it was not directly proportional, as other parameters influenced sound level. Suggestions for acoustic treatment of surfaces were made, together with suggestions for treatment and placement of furniture and for compartmenting the interior space. An example was given of a large dining area (2,280 m3) in which the beneficial effects of acoustic treatment of ceiling and of walls separately was demonstrated, the sound level being reduced by 4-8 dbA. It was recommended that persons at all levels, from administrators to the children themselves become aware of the necessity to lower noise levels to facilitate relaxation and communication at meal time and to control noise to innocuous levels.