Acoustical evaluation of preschool classrooms

An investigation was made of the acoustical environments in the Berwick Preschool in response to complaints by the teachers. Reverberation times, background noise levels, and sound levels in the classrooms were measured for acoustical evaluation. None of the classroom reverberation times or background noise levels was found to be acceptable according to relevant criteria. A questionnaire was administered to the teachers to assess their subjective reactions to the acoustical and non-acoustical environments in the classrooms. Teachers agreed that the non-acoustical environments in the classrooms were acceptable but that the acoustical environments were not. To study improvements to the acoustical environments, eight classroom acoustical-treatment configurations, involving increased surface absorption or reduced room volume or both, were simulated and reverberation times predicted. RASTI speech-intelligibility measures were also predicted in each case for the unoccupied and occupied classroom, and for three talker voice levels. Under the assumptions made, RASTI values increased with decreasing reverberation time and, therefore, with decreased classroom volume and increased surface absorption. It was recommended that the classroom volumes be decreased and that appropriate sound-absorptive materials be added to the walls, or ceiling, or both—a horizontal suspended acoustical ceiling could be highly effective.