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# Sound - Room Absorption Characteristics

## Mean absorption coefficients and reverberation times in typical rooms.

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

Sound - Room Absorption Characteristics
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
Theater
Lecture hall
Office
Library
Flat
Hospital
Church
Large church
Factory
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.

## 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.
• ### Noise and Attenuation

Noise is usually defined as unwanted sound - noise, noise generation, silencers and attenuation in HVAC systems.

## 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 - Reverberation Time

The sound reverberation time indicates how long it takes until the sound pressure level in a room is decreased with 60 dB.
• ### 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 (2003). Sound - Room Absorption Characteristics. [online] Available at: https://www.engineeringtoolbox.com/room-absorption-sound-d_69.html [Accessed Day Month Year].

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6.3.17

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