Developments in Ceramic Materials Research

Definition (D50)
1
0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
0.55
0.5
The Use of Ceramic Pots in Old Worship Places 167
Effect of resonators on Definition
0.45
0 0.2 0.4 0.6 0.8 1 1.2
Resonators per unit volume
Figure 21. Effect of number of resonators per unit volume on EDT C 80, D 50.
To find experimentally the effect of resonators on the acoustic quality of a room, an
experiment was carried out in an old Byzantine Church (Santa Maritsa) by Zakinthinos et al
[50]. For the experiment 480 bottles, instead of pots, were used as resonators, with resonant
frequency of 211 Hz. The volume of the church was about 500 m 3 , giving a ratio of about 1
resonator per unit volume. The measurements performed at the far field of resonators.
Figure 22 shows the reverberation time in the church with (dotted line) and without the
resonators (solid line). It is clear from this figure that there is a decrease of T30 mainly in the
low frequency region (octave band analysis). This is a consequence of the increased
absorption at the corresponding frequencies.
s
1.7
1.5
1.3
1.1
0.9
Reverberation time (T30)
0_ bott
480 _bott
0.7
63 125 250 500 1000 2000 4000
Figure 22. Effect of resonators on reverberation time T30.
1/1 octave band center frequency (Hz)