FISHERY BULLETIN: VOL. 84, NO. 2 



moans varied widely in duration and frequency (Hz). 

 Of the 93 miscellaneous moans analyzed (Table 2), 

 the principal sound energy occurred at a mean fre- 

 quency of 124 Hz; that of individual moans varied 

 from 70 to 245 Hz. Seventy-three percent of these 

 sounds exhibited frequency shifts (mean of 15.2 Hz) 

 that were downward or upward, or a combination 

 thereof. The mean duration of the moans was 0.42 



s (range, 0.2 to 1.5). These sounds occurred at inter- 

 vals of 0.2 to 9 min. 



The Bryde whale that apparently was attracted to 

 the ship (Contact 2) did not emit moans when very 

 closeby. The received overall sound level for a typical 

 moan, when this whale was estimated to be 300 m 

 away, was 102 dB. Assuming a spherical spreading 

 loss of 20 log 10 1.094(R), R being distance in 



Table 2.— Analysis of whale sounds. 



3- 



3- 



X 



> 



o 



o 



2 



1 



3- 

 2- 



1 



* * v - — • 





0.5 1.0 



K 



WATER-BORNE 



4- 

 3- 

 2- 



Kfi 







- » ^ . - -- 

 - 





a. 



•'*" . 



*r~ 



o 



0.5 L0 1.5 0.5 1.0 1.5 



TIME IN SECONDS 



Figure 4— Spectrograms of two blows from a Bryde whale recorded in air (upper) and in water (lower). The effective analyzing filter 



bandwidth was 20 Hz. 



364 



