Investigation of Acoustical Characteristics of Hüsrev Ağa Mosque And İbrahim Çelebi Mosque in Manisa, Turkey

Abstract

From past to present, the single-domed mosques, one of the most important building types for neighborhood, are generally used for daily worship. Although there are many studies on the architectural features and historical processes of single-domed mosques, it is observed that there is no comprehensive inventory of the acoustic conditions for them. It is important to evaluate acoustic conditions of historical mosques, which are accepted as cultural heritage, to identify the interventions that adversely affect these conditions and to suggest the restoration solutions for transmission them to next generations. In this study, acoustical measurements were taken two historical single- domed mosques in Manisa in order to characterize their acoustical quality and identify the effect of single dome on their acoustical parameters. They have the similar plan schema, a central dome and built in the same historical period. Reverberation time (T30), definition (D50), clarity (C80), STI and SPLA as objective room-acoustic indicators are presented for sample mosques. Hüsrev Ağa Mosque has estimated volume of 725 m³ and İbrahim Çelebi Mosque with estimated volume of 855 m³ [2]. The acoustical field measurements are performed for empty mosques in accordance with ISO 3382-2:2008 [3]. The values of T30unoccupied are 2.1 s for Hüsrev Ağa Mosque and 1.9 s for İbrahim Çelebi Mosque in the middle frequencies. T30 values for similar volumes with samples are higher than the optimum range (0.5 – 1.0 s) [1]. Although measured T30 values are good for the musical version of the Holy Quran, they are so high for praying mode and damage to the intelligibility of speech. (spatial impression) in the mosques is recommended between 1.2 and 1.25, is 1.4 in Hüsrev Ağa Mosque and 1.05 in İbrahim Çelebi Mosque [4]. SPL-A is measured with 6 dB difference among receiver points for both. It shows that desirable consistent sound pressure level distribution is provided involumes. In mid frequencies, measured C80 values are suitable for each function [5]. D50 values are under 50% (recommended) in mid frequencies. Mean values of STI in mosques are lies between 48% to 58% which means a “Fair” speech intelligibility [6]. In conclusion, mosques were suitable for musical version of Holy Quran. However, the speech intelligibility is damaged by high T30 values. For the improvement of T30 values, restoration of historical mosques with original materials should be encouraged.