INTRODUCTION 
This report records the results of a survey of the 
biological sound present in a set of tape recordings obtained 
during an 8-day period in July 1963 off San Clemente Island 
in the San Nicolas Basin during sound propagation experi- 
mentation. The results of studies of the signal and ambient 
background levels have already been reported by Wenz et 
al.” * The propagation experiment involved a ''shallow" 
hydrophone in 60 fathoms about 1 mile off Eel Point on the 
west shore of San Clemente Island and a ''deep'’ hydrophone 
in 450 fathoms of water about 4 miles farther offshore to 
the west. Both hydrophones were mounted on tripods which 
rested on the bottom. The outputs of the hydrophones were 
recorded side-by-side on magnetic tape. These recordings 
yielded an average of 12 minutes of ambient noise sampling 
each hour continuously over the 8 days, 15-23 July. Details 
on instrumentation and procedure can be found in reference 1. 
The data tapes were recorded at 3.75 inches/sec. 
The recordings were played back through a three-range 
speaker system, one channel at a time, using a variable 
band-pass filter for audio analysis when necessary. In 
addition to monitoring at normal and double tape speeds, 
listening was also performed at a playback ratio of 4 to 1 
in order to raise the low-frequency sound (down to 20 c/s) 
to more suitable listening frequencies. The spectrographic 
equipment used was the Kay Electric Co. Sonagraph Model 
Recorder; the spectrum-time plots obtained are referred 
to in this report as ''Sonagrams."' 
* Superscript numbers denote references in the list at the 
end of this report. 
