An open window is an example of 100% sound absorption i.e. no reflection, whereas bathrooms have 'hard' reflective surfaces and therefore very low sound absorption properties
Sound Absorption Class classification of sound absorbers into Sound Absorption Classes A-E, according to BS EN ISO 11654, including frequencies 200-5000 Hz..
Sound Absorption Coefficient the fraction of sound energy absorbed by a material. It is expressed as a value between 1.0, perfect absorption (no reflection) and 0, zero absorption (total reflection). The value varies with frequency and angle of incidence, determined experimentally - see Sabin and Sabine's equation.
Sound Absorption Coefficient of 1 = 100% sound absorption - for example an open window.
Also known as Sabine Sound Absorption Coefficient
Atmospheric Sound Absorption over short distances (100 metres) atmospheric sound absorption may be ignored. At greater differences it can be significant particularly at frequencies above 1 kHz. It is temperature and humidity dependent.
Attenuation Coefficient under Sound Absorption Coefficient.
Equivalent Sound Absorption Area the sound absorber or soft furnishings, etc., required to produce the required reverberation time in a room.
Noise Reduction Coefficient : NRC a single-number rating system used to compare the sound-absorbing characteristics of building materials. A measurement of the acoustical absorption performance of a material, calculated by averaging its sound absorption coefficients at 250, 500, 1000 and 2000 Hz, expressed to the nearest multiple of 0.05.
Room Absorption Coefficient ratio of sabine absorption of a surface to the area of the surface.
Sabin a unit of sound absorption. A square metre of 100% absorbing material has a value of 1 metric sabin. An example of this would be a 1 m² open window. One square foot of 100% sound absorbing material has a value of 1 imperial sabin.
The Sabin Absorption is A = 0.921 Vd / c : the unit is the sabin. Wallace Sabine developed the Formulae
Sabine : Wallace Clement Sabine an American pioneer in architectural acoustics. He derived an expression for the duration T of the residual sound to decay below the audible intensity. The associated sound absorption unit was named after him - sabin without the e.
Sabine Absorption Coefficient Definition under Sound Absorption Coefficient DefinitionSabine Reverberation Equation under Reverberation
See also : Reverberation