482 



A (whales I to III, Figs. 2 to 4) and 

 one of type B (whale IV, Fig. 5)'. The 

 recording of whale IV was done in 

 1961 and is the only recording we have 

 from that year. Hence, our treating 

 whale IV's song as representative of a 

 type is an assumption: the possibility 

 remains that this whale was ab ant. 

 A clear example of song type A is 

 shown in Fig. 2 (whale I). This figure 

 shows sound spectrograms, at a greatly 

 reduced scale, for a complete pair of 

 songs. The pair of songs was lifted 

 from the middle of a continuous song 

 session that contained at least seven 

 songs (there may have been more, but 

 Watlington's tape ran out). The fre- 

 quency scale in all spectrograms shown 

 here is logarithmic, since that is rough- 

 ly the way in which the human ear 

 interprets frequency. Had we wished to 

 define precisely the frequency com- 

 ponents of each unit, we might have 

 favored a linear frequency display, but 

 our chief purpose was to facilitate com- 

 parisons between spectrograms and the 

 sounds they depict. The spectrograms 

 in Figs. 2 to 5 were made by the 

 exceedingly tedious process of extract- 

 ing successive 9.6-second segments of 

 tape-recorded sounds and analyzing 

 them on a Kay spectrograph (model 

 6061 B), being careful that no time on 



the tapes was omitted. The effective 

 filter bandwidth was 60 hertz, and the 

 highest "real time" frequency seen by 

 the spectrograph under these circum- 

 stances, 2000 hertz. 



Once the spectrograms were made, 

 the hundreds required for each song 

 were carefully matched, glued to large 

 sheets of paper, and photographically 

 reduced. Because the ocean is a noisy 

 place (some of the tapes include wave 

 noise, ship noise, dynamite blasts, and 

 distant whales), and because loud 

 sounds in the water are invariably fol- 

 lowed by trains of echoes, we have 

 isolated the whale sounds by tracing 

 -them on a separate sheet, thus omitting 

 echoes and noise. Our tracings also 

 exclude harmonics, since they are of 

 little or no consequence in establishing 

 sequences and are often spuriously 

 generated by the spectrograph (12). 

 The only sounds for which we have 

 traced harmonics are brief, pulsive 

 sounds that, to a human listener, are 

 atonal (even when slowed down) and 

 must therefore have a rich harmonic 

 structure. The tracings, of course, fail 

 to show variations in darkness of line 

 • — the only indication of intensity that 

 spectrograph machines provide. How- 

 ever, darkness of line, even on the 

 spectrograms shown here, can only be 



relied on to reveal relative intensities 

 within any particular 9.6-second sam- 

 ple, since the level of input to the spec- 

 trograph machine was often adjusted 

 between successive samples in order to 

 obtain the least distorted rendition. 

 However, a thick line indicates ocean 

 reverberations, in some cases, thus de- 

 noting a loud sound. 



From inspection of the spectro- 

 grams, it is immediately obvious that 

 phrases in most themes are repeated 

 several times before the whale moves 

 on to the next theme. As mentioned 

 above, we find it true of all song types 

 in our sample that, although the num- 

 ber of phrases in a theme is not con- 

 stant, the sequence of themes is. (For 

 example, the ordering of themes is 

 A,B,C,D,E ... and not A,B,D,C,E 

 . . .). We have no samples in which 

 a theme is not represented by at least 

 one phrase in every song, although in 

 rare cases a phrase may be uttered 

 incompletely or in highly modified 

 form (compare phrase 4 in the first 

 and second songs of whale III, Fig. 8). 

 Figures 6 to 9 compare themes in song 

 type A as sung by what we assume to 

 be different whales, since the songs 

 were recorded at different times. In 

 this analysis, all phrases within any 

 given theme are shown for each of 



r- f r 



rfiiii'if r r (fffiiiii' r r 



rr r- r rrrr r r if r r rff fff 



T-rrnrmr^ 



- r rrrrr r r rrrfrr r f nUllllW I I ,'linill!"/ TTTTrr 



V/HALE I 



. ,'r ' -rlr r ,,n I I I H' I I HHI" 



I 



r^ rr f . -^ I ' <- - r ^rf r 1,1 f '/llr r r- f r c,i I I \\\\ I I / I )l"l I I I / / 1 I / M I 



\ 



T^-n — J — ) / /lI'M/i /fir '■'- / — r-r. 



- I I I I r-r-rrt ri r / i ii , 



WHALE II 



■ , I -r r I t , 1 1 f j F 



. - / ■ / n 1 1 1 I ' II' I ' ' m 1 ; ( .'i ' mil 



WHALE III 



Fig. 7. Theme 2 consists of one long phrase. Note that, in the second song of whale 11, this theme is three limes as long as in 

 song 1. The interunit spacing of this theme also varies considerably from song to song of the same whale. 



