This study aims to discuss the sound absorption properties of the composite perforated plate and the porous asbestos fiber. When the sound absorption properties of a perforated plate, together with the attached porous asbestos fiber, and the rear air gap have been altered, it will affect the sound-absorbing rate, as well as how the sound absorption capacity will be increased in low frequency bandwidth.
Conclusions drawn from latest research results:
The four-point conclusions listed below were drawn from the experiment on the sound-absorbing characteristic of single level perforated plates and porous asbestos fiber materials.
(1) (i) When the parameters of the sound absorption of perforated plates are equal, the sound absorption rate of the perforated wood plates is better than that of a perforated acrylic board.
(ii) When the sheet materials of perforated plates are the same, the bore diameter size and depth of the bore diameter will affect the absorption qualities within the perforated plates sound absorption parameter. When the bore diameter is smaller, the sound absorption rate obtained is more favorable. Likewise, when bore diameter depth is deeper, the sound absorption rate obtained is more favorable.
(iii) When an asbestos fiber material is attached to the perforated plate, the sound absorption rate is evidently better compared to a perforated plate without the asbestos fiber material.
(iv) When the rear air gap of the perforated plate is bigger, the sound absorption rate likewise increases. Nevertheless, to achieve a more effective sound absorption rate, attachment of an asbestos fiber material is still required.
(2) The experiment result reveals that the efficiency of the sound absorption properties of the composite perforated plate and the porous asbestos fiber material, when applied on different bandwidths, shows corresponding merits and defects. To aim at increasing its strong points, the sound absorption capacity of the bandwidth is required.
(3) The method in improving the sound absorption rate of low frequency
bandwidth is to use a tuning tube and a perforated tuning tube on the
sheet materials. Then using a perforated wood plate under the same
conditions, a series of comparison was done. Thus, it was discovered
that the sound absorption rate of the low frequency bandwidth clearly