Abstract
Experimental investigations were conducted to evaluate the sound absorption property of porous mortar（POM）boards with 30mm in thickness. The test variables were the particle size of fine aggregate（0.6-1.2, 1.2-2.5, and 2.5-5mm）and the target voids（10, 20, and 30％）. The tests were carried out by adapting an in-situ measurement method using ensemble averaging technique, i.e. EA method. The main results obtained are as follows：（1）the first peak of absorption coefficient shifts to a high-frequency band and the peak and dip values become greater by increasing the particle size of fine aggregate and the void ratio of POM；（2）POM with 10％ in void ratio possesses very low absorption coefficient regardless of its particle size；and（3）POM with fine aggregate of 0.6-1.2mm possesses the sound absorption property with which a wide frequency band is covered as compared with POM with fine aggregate of over 1.2mm.
