THE ACCURACY OF REVERBERATION TIME PREDICTIONS FOR GENERAL TEACHING SPACES

The Building Regulations Approved Document E Requirement E4 (ADE) makes it mandatory for teaching spaces within a school building to ‘…be designed and constructed in such a way that it has the acoustic conditions and the insulation against disturbance by noise appropriate to its intended use1 .’ The UK Building Bulletin 93:2015 (BB93) is considered an appropriate means of compliance with Requirement E42 . One of the main acoustic criteria for teaching spaces is to meet the Reverberation Time (RT) targets as it is important to provide a controlled acoustic environment in which the teachers’ and students’ voices can be clearly heard and are intelligible. By providing a suitable RT, the build-up of sound within a classroom is also controlled, reducing the need for a teacher to raise their voice and the possible health impacts this can have. Acoustics consultants therefore undertake design calculations to determine the amount of absorption necessary within each teaching space to meet the reverberation time targets that are listed within Table 6 of BB932 . Although testing of schools is not mandatory under BB93, post construction acoustic tests are often carried out. It is important to meet the design criteria as efficiently as possible. Calculations for the amount of materials required to meet targets need to be as accurate as possible, without overengineering a solution. The aim of this study is to critically evaluate two assessment methods for the estimation of the reverberation time in enclosed spaces (an analytical method and geometrical/ray tracing method) and to compare these results with the measured reverberation time within the completed classrooms to assess how accurate the predicted assessments are against actual in-situ measurements.