Prof, Helmholtz on Vowel Sounds. 85 
these I then added the third, and gradually several others, and 
endeavoured to imitate with the voice the sounds thus pro- 
duced. Thus I learnt by degrees to imitate the different sounds 
of the vowels more or less completely ; U, O, Oe, E were pretty 
good and distinct; I, Ue somewhat less so, for here the whis- 
tling of the air through the mouth, to whose different characters 
Donder called attention, is comparatively loudest; A and Ae 
were still worse, because here we require the combination of a 
great number of notes, the intensity of each of which cannot be 
so completely regulated; for A, in fact, a series of higher notes, 
for which I had no forks, were requisite. 
It may be remarked that, in general, the vowel-sounds com- 
posed by means of tuning-forks are more similar to those of the 
human voice when singing than when speaking. In the dry 
sound of our ordinary speech another kind of intonation is 
chosen, in which the primary note is much less prominent than 
the higher incidental notes and noises; by this means, in fact, 
the differences of tone become more evident than they do in sing- 
ing, where the primary note becomes more intense, and thus 
hides the incidental notes more completely. The artificially pro- 
duced vowels bear the strongest resemblance to those which are 
heard when we sing those vowels loudly into the interior of a 
pianoforte. The following are the particulars of my results :— 
The simple primary note, compared with the compound sounds, 
had the tone of U. The vowel is somewhat more distinct when 
the primary note is weakly accompanied by the third note. 
O is imitated when the primary note is powerfully accompa- 
nied by its higher octave. A very weak accompaniment of the 
third and fourth notes is advantageous, though not necessary. 
E is especially characterized by the third note, the second 
being moderately strong. The fourth and fifth may also be 
weakly sounded, 
The transition from O to E, therefore, follows from diminish- 
ing the second and increasing the third note. 
Oe ensues when both these secondary notes are loud. 
Ue arises when the primary note is accompanied by a third 
note of moderate strength. 
For I, the primary note must be weakened, the second, in 
comparison with the primary note, must be strong, the third 
very weak, the fourth, which is characteristic of this vowel, 
must be loud, and the fifth moderately strong. The weak notes, 
such as the third and fifth, may be omitted without causing 
any essential change of quality. 
For A and Ae, on the contrary, the bigher incidental notes 
are characteristic; the second note may be quite omitted, the 
third may be weakly given, but the higher notes must be 
