COMPARING THE ACOUSTICS OF MOSQUES AND BYZANTINE CHURCHES 
P. Fausti, R. Pompoli, N. Prodi 
Dipatimento di Ingegneria Engineering, Università di Ferrara 
Via Saragat 1, 44100 Ferrara, Italia 
(pafusti,rpompoli,nprodi)@ ing.unife.it 
KEY WORDS: Acoustics, cultural heritage, churches, mosques 
ABSTRACT: 
This work is based on the activities of the Department of Engineering of the University of Ferrara (Italy) within the CAHRISMA 
Project (EU Contract ICA3-CT-1999-00007, Conservation of the Acoustical Heritage and Revival of Sinan's Mosques Acoustics - 
CAHRISMA, 2000 - 2003). The project deals with the means of qualifying and enhancing the acoustical heritage of mosques and 
byzantine churches. The group carried out the acoustical measurements inside a selected group of spaces of worship and 
systematically collected their primary acoustical data. By successive processing, the main features of the two types of enclosures can 
be described and compared. The transition from the acoustics of a byzantine church to that of a mosque is also analyzed thanks to the 
architectural similarity between the former St. Segius and St. Bacchus church in Istanbul (now Kucuk Ayasofia mosque) and the 
Basilica of St. Vitale and St. Agricola in Ravenna, Italy. 
1. INTRODUCTION 
Within the CAHRISMA project (Karabiber 2000) six spaces 
were selected and acoustically measured, namely: mosques - 
Suleymanie, Selyimie, Sokullu and the byzantine churches - St. 
Irene, St.Sofia (now museum), St. Sergius and St.Bacchus. The 
measurements in Istanbul took place in two separate sessions. 
The first at the end of May 2000 (Sokullu and SS. Sergius and 
Bacchus) and the second in October 2000 (Suleymanie, 
Selyimie, St. Irene and St.Sofia). 
The measured mosques show heights comparable with the plan 
dimensions and are composed of a wide central volume, 
suiTounded by partly uncoupled galleries and balconies. These 
buildings have a huge slightly lowered dome, resting on pillars 
and on inferior orders of half domes. The materials covering the 
ceilings and walls are decorated plasters, marbles, stone and 
ceramics, all of them scarcely sound-absorbing. On the contrary 
the floor, though made of stone, is completely covered with 
carpets. 
Regarding the byzantine churches, they have an octagonal plan 
(or greek cross plan in the case of St. Irene) and present a wide 
gallery on the sides surmounted by a high balcony. All of them 
are covered by a dome of variable height. The interior finishing 
materials differ from mosques and also from one church to the 
other. In fact, while in the church of St. Sofia many surfaces 
were covered by mosaics or marble, in the church of S. Irene the 
walls and ceiling are made of stone and bricks. Inside St. 
Sergius and St. Bacchus most of the lateral walls are finished 
with painted plaster. The volumes of selected environments 
range between the 5700m 3 of Sokullu and the astonishing figure 
of 180000m 3 for St. Sofia. 
To the original group of measured spaces, also the byzantine 
church of S.Vitale was later added though not expressly 
scheduled in the project. This was done because of the 
architectural similarity between this byzantine church with the 
church of St. Sergius and St. Bacchus. The main difference 
between these two last worship spaces is that St. Vitale, having 
a volume of nearly 25800m 3 , is still equipped with a reflective 
floor as it was in its origin. On the contrary the church of SS. 
Sergius and Bacchus is today used as a mosque with a sound 
absorbing floor. For this reason its acoustical characteristics are 
better explained and consistent if it is examined as a mosque, 
and this will be actually done below. 
In the following the results of the acoustical measurements in 
the selected rooms will be resumed and commented in order to 
present the sound fields in mosques and byzantine churches. 
2. THE ACOUSTICAL MEASUREMENTS 
2.1 The positions of the sound sources and of the receivers 
Inside each space of worship a grid of receivers was set with 
attention to the covering of the most significant areas occupied 
by the congregation and by the leaders. Typically inside 
mosques three positions for the sound source were examined, 
namely Mimbar, Mihrap and Mahfel. These correspond to the 
locations of the main singer during the services, and are far 
apart from each other. It is important to obtain this sampling of 
the source because the liturgy is strictly connected to the 
singers’ position. 
As regards the byzantine churches generally three positions for 
the sound source were chosen, all of them located in the area 
close to the altar. In fact this is by far the most important area 
for the celebrating priest. The distribution of receivers covered 
in each space the main floor, the gallery and the balcony which 
are found both in mosques and byzantine churches. In Fig. 1 a 
typical plan with reference to positions of sound sources and 
receivers is shown. The measurements were taken with only a 
small group of researchers inside the rooms or with some 
reduced group of tourists inside the mosques. The conditions of 
occupancy were in any case to be regarded as “unoccupied”. 
2.2 The measurement chain 
The measurement chain was the same in all of the spaces for 
worship. The parts of the chain are recalled in Table 1, where 
each task has the indication of the respective instrumentation.