Cl PA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
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Keeping 
the level at 2 m and changing the pit back wall results in an 
increase in favour of the singer throughout the hall. The last 
change was the barrier’s material with the pit floor at 2 m and 
the pit back wall material fixed. In the results the behaviour for 
both cases is the same. 
Considering the existing equilibrium between singer-conductor- 
orchestra no remarkable changes are noted except when the pit 
floor is at 1.5 m. In this case the conductor has no significant 
changes in the way he hears the orchestra and the singer. On the 
other hand the singer hears the orchestra 3 dB stronger than in 
other conditions. 
Fig.3 The balance is shown: (a, b) the balance in the stalls at 
500-1000 Hz and 2000-4000 Hz; (c, d) the balance 
in the balconies at 500-1000 Hz and 2000-4000 Hz. 
Figure 4 shows the equilibrium between singer-conductor- 
orchestra. Previous studies suggested that the sound pressure 
level produced by the orchestra at the singer’s ear has to be 10 
to 20 dB lower than the sound power level of his voice. 
b) Simulated level of the orchestra and singer at the 
8Q conductor's position 2000-4000Hz 
79 T ■■ ■ ■ — 
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■ ■ 
■ ■ 
pit 1,5m pit 2m pit back wall barrier 
changes X orchestra «singer 
(c) Simulated level of the orchestra at the singer's 
position _ 500-1000 Hz - 2000-4000 Hz 
pit 1.5m pit 2m pit back wall barrier 
changes j xorchestra 500-1000Hz ■ orchestra 2000-4000Hz 
Fig.4 a) and b) show the way in which the conductor can hear 
the orchestra and the singer a) at 500-1000 Hz and 
b) at 2000-4000 Hz; c) show the way in which the 
singer can hear the orchestra at 500-1000 Hz and at 
2000-4000 Hz. 
2.5 Discussion 
The significant difference, based on the pit floor level, between 
stalls and balconies is based on the fact that independently to 
the pit level, all the positions in the balconies can see the 
sources in the pit. This means that the direct sound can reach all 
the balconies. On the other hand no direct sound can reach the 
stalls. This part of the theatre is reached by reflections coming 
from the ceiling. Moving up the pit floor the reflection path is 
reduced and the sound pressure level increased. The pit back 
wall contributes to reflect the sound throughout the hall. 
Changing this material has an influence on the reflections in the 
stalls and in the balconies. Figure 5 illustrates this. 
In all this study the equilibrium between singer-conductor- 
orchestra was considered too. The pit side material of the barrier