THE CATEGORIES OF BIOLOGICAL SOUND 
Table 1 and the first nine figures show some charac- 
teristics of the sounds found to be common in these San 
Nicolas Basin recordings. The meanings of the terminology 
used in the table will become more clear as each sound 
type is described. Each of the first five figures describes 
TABLE 1. MAIN TYPES OF BIOLOGICAL SOUND HEARD 
Frequency | Max. Sound Pulse 
Range S/N |Duration | Period | Duration | Period 
Assigned name (c/s) (c/s) (sec) (sec) (msec) | (msec) 
2. Rhythmic 
Grunt 90-300 125 350 
3. Motorboating | 120-1000 Rem enti arieser 75 
4, Barking 
(''yelp") ca 2000 oe 
6. Low-Freq. 
Groan 20-70 --- 
fi. 20%e/is tong 
Pulse I) O42 --- 
8. 20c/s Short 
Pulse 19-40 20 0.6 = 600 ee 
one of the five most distinctive and common biological 
sounds in the recordings. Each figure consists of at least 
one Sonagram, which shows a combination of frequency, 
time, and gross relative amplitude; a spectrum plot froma 
