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Reverberation
Sound quality in offices, classrooms, meeting rooms, or any enclosed space, can be compromised by high levels of reflected sound, known as Reverberation. This phenomenon leads to a build-up of sound level within the space, which often has negative affects on speech communication and comfort levels.
In some environments, high levels of reverberation are welcome - churches and concert halls for example. In schools, however high levels of reverberation are not desirable and can have many negative effects.
The sound of speech passes directly to the ears of the student via the direct sound path (as illustrated above). Another part of the sound travels to various surfaces in the room and reaches students via reflected sound paths. This reflected sound reaches students from many directions at close intervals: thereby causing the reverberant effect.
Effect of Reverberation : Speech intelligibility
Where the reverberation is high, the student is still receiving the reflected sounds of previous syllables at the same time as they are trying to cope with the direct sound of later syllables. This makes any speech unintelligible.
Measurement of Reverberation : Reverberation Time (Rt)
The measure of reverberation is in time - it is a measure of how long it takes for a sound to decay. It may vary from half a second in an ordinary living room to 8 seconds or more in a large assembly hall. A classroom or teaching space with a long reverberation time of several seconds will cause syllables to be prolonged so that they overlap and hence degrade speech intelligibility.
How to reduce Reverberation : Absorption
Adding acoustic absorption panels or tiles will reduce the reverberation time and will improve speech intelligibility. The control and design of reverberation is based on the relative extent of sound absorption surfaces and materials that can be applied to the space.
Examples of absorption in a school gym and a lecture theatre
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Schools/Meeting Rooms
