117 



Fig. 4A. Signal from 20 -foot 

 Projector Hydrophone at 100 feet 

 Range 12,450 yards. 



Fig. 4B. Noise-field Hydrohpne 



at 100 feet Receiver Attenuator at Odb 



ure 4b the directional character of the noise field 100 feet below the measuring 

 ship is depicted. In figure 4b it can be seen that the major noise appears to be 

 coming from a bearing of about 35° with the vertical. This corresponds roughly 

 with the location of machinery spaces on the ship from which the naeasurement 

 was taken. 



When utilized from a suitable platform, it is felt that the instrument de- 

 scribed will permit an examination of the directional characteristics of noise 

 fields over the frequency range of 1 to 8 kc. Refinements of the instrument 

 should incorporate side lobe suppression even at the expense of somewhat broad- 

 er directivity patterns. 



A somewhat simpler system useful for a study of directional distribution 



US& REHOSOTN USS REHOBOTH 



Fig. 5A. Simultaneous Wind Force 

 Observations (Beaufort Scale -- 

 Cruise NINE) 



Fig. 5B. Simultaneous Wind Force 

 Observations (Beaufort Scale -- 

 Cruise TEN). 



