1975] 
Willey — Sound Production in Arphia 
327 
AIR 
5. 1 cm 
Fig. 2. Schema of the water- and air-cooled observation cage, sagittal 
section. In practise, the water flow was discontinued during filming, but 
not more than five minutes at a time, (a) Tape dam, (b) wire mesh 
screen (nine grids/cm 2 ), (c) plastic foam wind-screening, (d) glass wool 
acoustical packing, (e) opal plastic cylinder. 
cooled cage (Fig. 2). The distance was only 2 or 3 cm and there- 
fore time delay due to speed of sound in air was negligible. Figure 9 
illustrates the maximum calculated delay (0.1 msec, frame duration 
of 1.2 msec, shutter speed of 0.5 msec). Electronic delay also can 
be considered negligible. The microphone was protected from the 
noise of the air stream in the cage by a glass wool material which 
effectively dampened the acoustical components of the air stream. 
This is the same material used in the audiometric room to silence 
the ventilation system. The microphone, powered by mercury bat- 
teries totalling 7.5 V, was connected to the CRO by means of a 
20 ft (6 m) extension cord and Acoustic Designs ADM 667 pre- 
amplifier. 
The subjects were illuminated by three General Electric Com- 
pany MG- 1 movie lights with 500W mini-lamps. One light was 
attached to the camera outside the audiometric room and was used 
at full intensity for front lighting; the other two lights were used 
inside the room to side-light the insects (Fig. 2). The inside cylinder 
of the cage is of white opal plastic to diffuse the incoming side light. 
