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Sound - Room Absorption Characteristics

Mean absorption coefficients and reverberation times in typical rooms.

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The table below indicates mean sound absorption coefficient  - αm - and reverberation time - Ta - for some typical rooms.

Room CharacteristicsVery SoftSoftNormalHardVery Hard
Reverberation time
- Ta -
0.2 < Ta < 0.25 0.4 < Ta < 0.5 0.9 < Ta < 1.1 1.8 < Ta < 2.2 2.5 < Ta < 4.5
Typical Room Radio and TV studio Restaurant
Lecture hall
Large church
Mean sound absorption coefficient
- αm -
0.40 0.25 0.15 0.10 0.05

The mean sound absorption coefficient should be calculated when more accurate values are needed.

The diagram below can be used to determine the sound absorption in rooms of different sizes and with different accoustic characteristics.

Sound Room Absorption

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  • Engineering ToolBox, (2003). Sound - Room Absorption Characteristics. [online] Available at: [Accessed Day Mo. Year].

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