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# Sound - Reverberation Time

## The sound reverberation time indicates how long it takes until the sound pressure level in a room is decreased with 60 dB.

Reverberant sound is the collection of all reflected sounds.

The Reverberation Time - Ta - for a room is the time it takes before the sound pressure level has decreased with 60 dB after the sound source is terminated and can be calculated as

Ta = 0.16 V / A                     (1)

where

Ta = reverberation time (s)

V = room volume (m3)

A = the total sound absorption of the room (m2 Sabine)

Ta = 0.16 V / [(A /αm)ln (1 / (1 - αm))]                       (2)

Note! The sound absorption of the room - A - vary with sound frequency, and so do the reverberation time - Ta.

### Recommended Sound Reverberation Times for some typical Rooms

Sound - Reverberation Time
Recommended Reverberation Time - Ta - (s)
Room Volume
(m3)
Conference room, school, cinemaConcert Hall, Normal MusicChurch, Organ Music
10000 1.0 1.5 2.0
1000 0.8 1.3 1.6
100 0.6 1.1 1.2

#### Example - Sound Reverberation Time for a Room

The sound reverberation time for a room with mean sound absorption coefficient 0.2, total sound total sound absorption 12.2 m2 Sabine and room volume 4 m3 - can be calculated with equation (1) as

Ta = 0.16 (4 m3) / (12.2 m2 Sabine)

= 0.05 s

## Related Topics

• ### Acoustics

Room acoustics and acoustic properties. decibel A, B and C calculations. Noise Rating (NR) curves. Sound transmission through walls. Calculate sound pressure, sound intensity and sound attenuation.

## Related Documents

• ### Propagation of Sound Indoors - the Room Constant

In a room the sound or noise will reach the receiver as direct and reverberant sound.
• ### Sound - Room Absorption Characteristics

Mean absorption coefficients and reverberation times in typical rooms.
• ### Sound - Room Absorption Coefficients

Room sound absorption and absorption coefficients for common materials like plaster walls, brickwork, plywood panels and more.
• ### Sound - Room Attenuation in Direct Sound Fields

Room size, absorption characteristics - and attenuation in direct sound fields.

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## Citation

• The Engineering ToolBox (2004). Sound - Reverberation Time. [online] Available at: https://www.engineeringtoolbox.com/reverberation-time-d_724.html [Accessed Day Month Year].

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