The mean number of 20 c/s Long Pulses per sample 
(10.9 deep and 14.6 shallow) corresponds to about 55 and 73 
per hour, respectively, or of the order of one per minute. 
The counting was influenced by interpretation as to what 
constituted a Pulse, because at times the sounds were 
superimposed on each other causing a continuous and 
multiple jumble of sound. Counting was particularly sub- 
jective when the sounds were barely audible. For these 
reasons quantitative description of the Long Pulses, such 
as in figure 12, is open to question. This report does not 
describe all the variety of sounds observed, but only the 
frequent, repetitive sounds, especially those that have 
substantial influence on overall ambient levels. Of the 
other sounds, infrequent and sometimes obscure, one de- 
serving at least passing comment can best be described as 
consisting of isolated clicks or pops doubtless from bio- 
logical sources. Although these clicks and pops were 
sparsely spread, so that they had no effect upon mean 
ambient levels, they were found in at least 50 percent of 
the deep samples and 10 percent of the shallow samples. 
They were also slightly more frequent from midnight to 
noon than from noon to midnight. 
Wenz’ has discussed the phenomenon of hearing 
pinniped barking from a bottom-mounted hydrophone at 
360 ft depth, and the implication was that the pinniped may 
be capable of barking while completely submerged. In the 
present study the deep receiving hydrophone at 2700 feet 
(450 fathoms) picked up pinniped sounds with good S/N. 
DeVries and Wohlschlag”” have recorded dives of the 
Weddell seal in Antarctica to depths of approximately 
M50 feet: 
The National Science Foundation has recently re- 
ported (through a publicity release’) that: (1) The sub- 
merged Weddell seal produces a wide variety of noises 
without opening its mouth or nostrils. (2) The seal sounds 
are heard at depths of hundreds of feet. (3) Scuba divers 
associate certain throat and head movements with particu- 
lar sounds. In addition, Schusterman, Kellogg, and Rice 
oi 
