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New perspectives to save cultural heritage
Altan, M. Orhan

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
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.
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
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.
2.1 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.