Teaching Space Acoustics

There may be an increase in the use of unusual teaching spaces as schools adapt to new challenges. For instance, the use of sports halls, foyers and other reverberant spaces as classrooms will present acoustic problems. Long reverberation times make it difficult to understand speech if you are more than a metre or two away from the person talking. This is because the sound energy bouncing around the room masks the words being spoken.

The solution is to reduce the reverberation time by the addition of absorption to improve intelligibility. We measure the current reverberation time and calculate how much absorption is required to bring it down to an acceptable level for the room concerned. An acceptable level varies depending on room volume.

We recently undertook a project for a school’s large sports hall. The school had been given estimates based on predictive calculations alone indicating a reverberation time in excess of 6 seconds. When we measured the actual acoustics of the room we found these to be inaccurate and would have resulted in the installation of unnecessary quantities of absorption. It turned out that there was absorption hidden from view in the ceiling mounted heating system resulting in a time of 3.9 seconds.

We set a target reverberation time of 2 seconds in line with BB93 guidance for a room of this volume and type. In fact, we bettered this and brought it down to 1.6 seconds which you can see in the excerpt from the report below.

Published by Paul Furness

I have over thirty years’ experience in the design and installation of audio visual systems. I have designed and project managed the implementation of systems for corporate boardrooms, meeting rooms and conference facilities as well as classrooms, lecture theatres, halls and churches.

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