Reverberation time
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Reverberation time

Reverberation Time. Room acoustic descriptors.

The reverberation time is defined as the time it takes for sound to decrease by 60 dB. To determine the length of this time, different parts of the reverberation curve are used.

The descriptors T20 and T30 are usually called “late reverberation times” as they measure at the later part of the curve. EDT is called “early reverberation” and is considered to better reflect how we perceive the reverberance in the room.

When measuring Early Decay Time (EDT), an interval of 10 dB is used. At T20, an interval of 20 dB is used. When determining T20, the evaluation does not start until after the sound level has already fallen by 5 dB. At T30, an interval of 30 dB is used and here too, the evaluation starts after the sound level as fallen by 5 dB. If the reverberation curve is straight, the EDT, T20, and T30 will all produce the same value. In practice, the reverberation curve is seldom straight (dashed line), which means that the descriptors will differ.

  

 

Perceived attribute

Objective descriptor

Designation

Unit

Explanation

Standard

Reverberation times

Measures speed at which sound disappears in a room.

 

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Monk Sherborne,
Tadley, RG26 5PP
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Contact us

Saint-Gobain Ecophon Old Brick Kiln,
Monk Sherborne,
Tadley, RG26 5PP
General enquiries Tel: 01256 850977 
 
Sales office, for orders and stock information Tel: 01256 855220 / Fax: 01256 850600
 
Technical and product advice Tel: 01256 855250 / technical@ecophon.co.uk
 
Fax: 01256 851550
Social: LinkedIn  |  Twitter  |  You Tube