Sound Absorption, sound energy is 'absorbed', to some extent, by the different media that sound waves encounter, along their transmission path, from the source to the receiver.
An open window is an example of 100% sound absorption i.e. no reflection, whereas bathrooms usually have sound reflective surfaces and therefore very low sound absorption properties, resulting in multiple reflections in the room and a diffused sound field.
Sound Absorption Coefficientis the fraction of sound energy absorbed by a material. 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. Metric unit, sabin per square metre
Sound Absorption Coefficient Definition is also known as the sabine absorption coefficient
Related Terms - listed alphabetically
Absorption Coefficient under sound absorption coefficient
Absorption Definition IEC 702-02-12,conversion of electromagnetic or acoustic wave energy into another form of energy, for instance heat, by interaction with matter.
Absorption Factor, the property of a body that determines the fraction of the incident radiation or sound flux absorbed by the body. Also known as absorptivity
Absorption Loss Definition IEC 801-23-40,that part of the transmission loss due to the dissipation or conversion of sound energy, either within the medium or attendant upon a reflection.
Atmospheric Sound Absorptionover short distances (100 metres) atmospheric sound absorption may be ignored. At greater differences it can be significant particularly at frequencies above 1 kHz and it is temperature and humidity dependent.
Equivalent Sound Absorption Area (A),is the sound absorber or soft furnishings, etc., required to produce the required reverberation time in a room.
Equivalent Absorption Area of an Object or of a Surface Definition IEC 801-31-06,area of a surface having a sound power absorption coefficient of unity that would absorb the same amount of sound power in a reverberant room with a diffuse sound field as the object or the surface. In the саsе of a surface, the equivalent absorption area is the product of the area of the surface and its sound power absorption coefficient
Impedance Tubeis a method for measuring sound absorption coefficients by means of standing (stationary) waves in a tube, also known as a standing wave tube
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.
Passive Sound Absorbersdissipate sound energy as heat.
Reference Sound Absorption (Ao)when measuring sound insulation between rooms it is common practice to normalize the measured levels to a reference sound absorption of 10 m2
Room Absorption Coefficientis the ratio of Sabine absorption of a surface to the area of the surface.
Room Absorption Definition IEC 801-31-11,is the sum of Sabine absorption due to objects and surfaces in a room, and due to dissipation of sound energy in the medium within the room.
Sabin is a unit of sound absorption.One square metre of 100% sound 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.
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 Definition IEC 801-31-10,sound absorption defined by the Sabine reverberation-time equation The unit of Sabine absorption is the decibel metre-squared, sometimes known as the metric sabin.
Sabine Absorption Coefficient Definition IEC 801-31-12,quotient of Sabine absorption of a surface by the area of the surface. Is also known as the sound absorption coefficient
● Note : with αi as the Sabine absorption coefficient of the i-th surface whose area is Si, the Sabine absorption attributed to the surface is Ai = Siαi.
Sabine Reverberation-time Equation under reverberation time
Sound Absorbers for use in buildings are ranked A to E, as specified in BS EN ISO 11654.
Sound Reduction Coefficient under noise reduction coefficient