In historical building restorations, the selection of mortar mixture type should be determined in accordance with particular requirements of the historical buildings. In this study, it has been examined that how the sound absorption coefficients of plaster layers can be increased in ways that are compatible with the historical structures. In the scope of lab analyses, mixtures produced with river sand aggregate and hydraulic lime binder were examined. Material properties of samples were investigated by means of the experimental analyses which can be listed as sound absorption, open porosity, capillarity of water absorption, flexural and compressive strength. The effects of the binder ratio and aggregate particle size range in mortar mixtures were investigated in order to increase the sound absorption in the plaster layer. Moreover, the effects of polypropylene fiber, flax fiber and crumb rubber additive were investigated as well. After the measurement results are obtained, the outcomes of the experiments were discussed. In this research, it is demonstrated that the sound absorption can be increased by the content of the mixture. Especially, it is observed that the reduction of the binder ratio in the mixture may increase sound absorption and the use of very fine aggregates in the mixture can adversely affect sound absorption. In brief, a systematic research was carried out in order to increase sound absorption coefficients in accordance with the content of the plasters used on historical buildings. (C) 2018 Elsevier Ltd. All rights reserved.