Developments in Ceramic Materials Research

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Dimitris Skarlatos, Tilemachos Zakinthinos and Ioanis Koumanoudis
Figure 10. Pots in medieval Scandinavian churches: Plugged vases (a, b) and vase partially filled with
ash.
3.4. Resonant Frequencies of Vases
The resonant frequencies of vases depend on their geometry. Measurements of Mijic et
al. showed that the resonant frequencies of resonators, found in Serbian Orthodox churches,
are within the range of 55.5 – 131 Hz. [2]. Measurements of Carvalho et al. in vases found in
Middle Age Churches in Switzerland and other countries, showed that their resonant
frequencies are within the range of 237- 444 Hz [7]. The resonant frequency of pots found in
the church of St. Andrews in UK is between 350-470 Hz [39]. Kayili estimated the resonant
frequencies of pots found in Blue Mosque as follows: pots with small opening, between 100
and 120 Hz and of pots with large opening between 180-200 Hz. [9]. The resonant frequency
of vases found in Greece was estimated to be between 131 and 447 Hz.
3.5. Number of Resonators Found in Places of Worship
In some places of worship it is impossible to determine the number of built-in resonators.
Some of them were covered by mortar during restoration work and in others parts of the walls
were missing. Generally, with some exceptions, the number of resonators found in places of
worship is usually small, inadequate to affect the acoustics of large spaces. The Villete church
located in Switzerland contains only 4 resonators and the Syens Church has 5 [4]. According
to Mijic [1] the greatest number of resonators found in a single church, is 24. Kayili [10]
found 144 resonators in Shehzade Mehmet Mosque, and 75 at the dome of the Blue mosque.
According to the same researcher, it is written in the building records of Suleymaniye
Mosque that 255 small jars have been bought and installed. Also the same researcher found at
Sokuullu Pasha Mosque, traces of holes believed to be the openings of resonators. There were
thirty six holes in the main dome and 42 to 45 in each of the quarter domes. In Bolognia the
cathedral of St. Pedronio, according to Crunell, contains more than four hundred resonators
and St. Ietro only twenty five [8]. St Andrews church in UK has a total of 23 vases placed in
the Chancel and the walls [Murphy]. Koumanoudis in 10 years of research has visited and
studied about 2,500 buildings (churches and monasteries) and found, in 168 of these
buildings, 1,057 walled-in vases. Out of these 147 were churches with 969 walled-in sound
vases, which correspond to an average number of 7 vases per church [5].