1879.] 



Studies in Acoustics. 



365 



more prominence to the second, third, and fonrth partials will result 

 in aw, while a bright ah is obtained by increasing the amplitude of 

 the fifth and sixth partials. 



22. A very good and full ah is obtained by having all the partials 

 equally represented, from the first to the eighth ; and this really pro- 

 bably takes place when the human voice pronounces this vowel, as, in 

 so doing, the mouth cavity is fully opened, so as to favour most of 

 the partials. 



23. The vowel sounds a and ee, when reproduced by most of the 

 ordinary phonographs, resemble respectively more o and oo. Also the 

 curves for a and ee, obtained by the phonautograph, fig. 2, resemble 

 those for o and oo. This shows, in the first instance, that neither 

 instrument is sensitive to the higher upper partials ; and, secondly, 

 that the lower partials for a must be similar to those in 0, and the 

 lower partials for ee must be the same as in oo. To prove this, two 

 disks were cut, one with a curve composed of the first, second, and 

 eighth partials, and the other of the first, third, and eighth partials. 

 The former, when sounded, produced a sound like ee, and the latter 

 more like a. 



24. The best ee has been obtained from a curve composed of the 

 best first, second, eighth, and sixteenth partials ; and d from a curve 

 composed of the first, third, and sixth or eighth partials ; but this 

 last curve can hardly be called satisfactory. 



25. Diagram 10 graphically illustrates the above facts, and the 

 following table gives them in a tabulated form : — 



Vowels. 







Partials with their Intensities. 





oo 



1. 



2. 



3. 













ff. 



mf. 



pp. 











ah 



1. 



2. 



3. 



4. 











mf. 



f. 



mf. 



p. 









o 



1. 



2. 



3. 



4. 



5. 



6. 8. 







p. 



P- 



p. 



mf. 



mf. 



p. p. 





a 



1. 





3. 







8. 







mf. 





mf. 







ff. 





ee 



1. 



2. 









8. 



16. 





mf. 



P- 









P- 



mf. 



Hence, although the reproduction of vowels was good, it was imper- 

 fect. This is due probably to the absolute impossibility of repro- 

 ducing the noises that accompany the last two vowels. 



26. One very curious result arising from the experiments with the 

 automatic phonograph was to show that, by varying the pitch, the 

 vowel sounds could be shifted, i.e., the curve which produced oo at a 

 low velocity becomes approximately at a higher velocity. similarly 

 becomes ah, ah becomes d, and d, ee. 



