الفهرس 
Study and evaluation of sound reduction index of different partition structures using sound pressure and vibration methods
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Abstract
Nowadays, protection against noise is one of the most essential requirements. The constructions must be designed in such a way that the noise level perceived by the occupants does not threat their health and does not disturb their life. In buildings, the airborne sound insulation is the most important physical quantity that assesses the acoustical quality of buildings or building elements. The use of lightweight partitions has become common in buildings as an alternative to traditional masonry partitions. The widespread use of lightweight partitions in various applications ranging from construction of buildings to workstation rooms has become of more interest. These materials are easy to install and it can achieve the sound insulation requirements with low cost and low overall surface weight. The purpose of this thesis is to evaluate the sound insulation behavior of different single and double lightweight partitions. In addition, to compare the experimental results with the theoretical model using Sharp’s prediction model.The measurements were carried out by using two methods. The first method is the sound pressure method (two room method), where it is standardized and its measurement procedure was done according to the requirements of ISO 140-3:1997. The second method is the vibration velocity method (not standardized) and its measurement procedure was done according to some criteria of ISO 10848-1:2006. Single and double layer partitions of 18mm plywood, 13mm gypsum board and 16mm gypsum board were used in this study. In the case of double layer partition, the double layers were separated by 5cm and 10cm air gap, where the air cavity was filled with absorbing materials either Rockwool or polyurethane. It is found that increasing the cavity depth leads to shifting in the resonance frequency to lower frequencies outside the range of interest. Filling the empty cavity with sound absorbing material cuts down the amplitude of the cavity resonance and makes the critical frequency that occurs due to the coincidence effect less sharp and reduces its amplitude, which means that the absorbing material is effective in increasing the sound insulation