Acoustic+2

=Classroom Acoustic=

There are two ways to reduce the Reverberation Time of a room: either the volume must be decreased or the sound absorption must be increased. Though decreasing the volume is not always an option, it is a viable alternative for many older classrooms with high ceilings. In such spaces, adding a suspended ceiling of sound-absorbing tile can significantly improve the acoustics by simultaneously decreasing the volume and increasing absorption. However, adding a suspended ceiling often requires new light fixtures and can interfere with tall windows.

When locating absorptive materials to reduce reverberation time, consider how they might help reduce echoes as well. Placing an absorptive material on the rear wall of a classroom prevents the teacher’s voice from reflecting back to the front of the room. While absorption is one way of minimizing reflected energy into the classroom, another approach utilizes diffusion. Placing a diffusing element on the rear wall of the classroom scatters the sound into many directions, so that the level in any one particular direction is greatly reduced. Flutter echo is a particularly significant problem when it occurs between the walls at the front of the room where the teacher is speaking. A simple way to test whether flutter echo is a problem is to stand near the center of the classroom, between parallel surfaces, and clap hands once sharply.

To be effective, partition walls should extend from the structural floor to the structural ceiling. Otherwise, sound from one room can easily pass through a lay-in acoustical tile ceiling, over the partition wall, and down through the lay-in ceiling of the next room. This is commonly overlooked when walls are added during renovations, such as when open-plan classrooms are partitioned.

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