Sound - Room Absorption Characteristics

Mean absorption coefficients and reverberation times in typical rooms

Room CharacteristicsReverberation Time - Ta (seconds)Typical RoomMean Sound Absorption Coefficient - αm
Very Soft0.2 < Ta < 0.25Radio and TV studio0.4
Soft0.4 < Ta < 0.5Restaurant, Theater, Lecture hall0.25
Normal0.9 < Ta < 1.1Office, Library, Flat0.15
Hard1.8 < Ta < 2.2Hospital, Church0.1
Very Hard2.5 < Ta < 4.5Large church, Factory0.05