】 【Weak current college building decoration materials of sound absorption coefficient calculation.

How to calculate building decoration materials of sound absorption coefficient
Measurement of sound absorption coefficient of the material in two ways, one is the reverberation room method, a standing wave tube method. Measurement of the reverberation room method for sound random incident sound absorption coefficient, that is, the sound from all directions into a material proportion of the energy loss, while standing wave tube method for the measurement of sound is the sound absorption coefficient of the incident, the incident angle of only 90 degrees. Two methods for measurement of sound absorption coefficient is different, works on the most frequently used is the reverberation room method for the measurement of sound absorption coefficient, because building practice sound incident are random. In some measurement report appears sound absorption coefficient is greater than 1, this is due to the measuring laboratory conditions and so, in theory, any material absorption of sound can not be greater than the incident sound absorption coefficient of energy, always less than 1. Any value greater than 1 for the measurement of sound absorption coefficient value in the actual acoustic engineering calculation cannot be used by more than 1, the maximum calculated by 1. In the room, the sound will soon fill every corner, therefore, the sound-absorbing materials placed in any room with sound-absorbing effect of the surface. Sound-absorbing material, the greater the sound absorption coefficient, the more the sound absorption area, acoustic effects.
Use ANSYS to calculate the sample sound absorption coefficient
Standing wave tube (main part is a cylindrical steel pipe), pipe inner diameter 9.5cm, 10cm, pipe length 100cm, pipe laying one end of the measured sample (a sound-absorbing material, made of cylindrical shape, just to put into the tube, the sample thickness 8cm), the other end of the tube has a sound source (trumpet), the tubes transmit a certain frequencies of sound waves, sound waves are propagated to the operation of air samples surface, part of the acoustic absorption by samples, and another part of the sound waves are reflected by reflection sound waves and incident propagation of sound waves in the opposite direction, after the overlay each other, in the formation of standing wave tube, wave formation of abdominal force maximum sound pressure, corrugated Division formed sound pressure minimal value, measured in experiments from samples of recent sound pressure Maxima and minima, the formula worked out samples of sound absorption coefficient.
Sonic impact sound absorption is to surface after the energy loss of sound absorption can reduce the room sound pressure level. Description of the sound absorption indicator is the sound absorption coefficient, represent a material absorption of sound energy and incident sound energy ratio. In theory, if a material is fully reflect a sound, so it's a = 0; if some materials will absorb all incident sound energy, then it's a = 1. In fact, all the materials of a number between 0 and 1, it is not possible all reflection, cannot be brought into full absorption. Different frequencies will have different sound absorption coefficient. The use of sound absorption coefficient of frequency characteristic curve describes the material in different frequency absorptivity. In accordance with ISO standards and national standards, sound absorption test report sound absorption coefficient of frequency range is 100-5KHz. The 100-5KHz of sound absorption coefficient by average value is the average absorption coefficient, the average absorption coefficient reflects the overall performance of the sound-absorbing materials.