HARMONIC ANALYSIS OF CERTAIN VOWEL SOUNDS. 769 
reinforced in one case as high as g” and a second partial as low as ¢’, and 
it is very probable that if the experiments had extended to lower notes we 
should have detected resonance at still lower pitches by the strengthening of 
the second partial. Without assuming that the primes below ¢ are reinforced 
at all, we see that this cavity is capable of reinforcing more or less strongly all 
tones falling between g’ and ¢’ at least. 
Further, it cannot be said that these analyses exhibit any epee oily strong 
resonance on or close to b,’, as was observed in the human 0. 
The artificial 6’s agree with those of the human voice in being composed almost 
wholly of the two first partials for notes above b. On fandg their third partials 
are more prominent than in the human 0’s, and they have in addition a moderate 
fourth partial ; their second partials, however, are not so strong relatively to the 
prime. On ¢ also there is a strong fourth partial. 
The property possessed by this irregularly-shaped gutta-percha cavity of 
reinforcing tones over a wide range of pitch, was confirmed by another and quite 
independent experiment. <A short tube was inserted into the neck of the bottle, 
in place of the reed, and the end of this tube was applied to the ear. The cavity 
was thus adapted to act as a resonator to sounds from outside. By striking in 
succession the keys of a pianoforte with this resonator applied to the ear we were 
able to observe the tones which were reinforced, by the peculiar bumming noise 
which they gave rise to in the bottle. On working down the scale, with the 
cavity arranged for the vowel sound 4, the first note at which resonance could 
be detected was gy”. It became stronger on g”, stronger still on /4, and exces- 
sively strong on 7”. One” it was nearly equally strong ; on ¢,” and d” weaker, 
but still very strong. On c¢” it again became very intense, and again fell off 
somewhat on lower notes. But even on g’ and / # there was much more reson- 
ance than could be accounted for by the reinforcement of the second partial in 
the note struck. The presence of the upper harmonics in the sound given by 
the pianoforte wires prevented this method of observing from being suitable to 
pitches below /’. But the above experiment sufficed to show the cavity had at 
least two, and probably more, proper tones, so closely grouped as to have the 
general effect of enabling it to strengthen by resonance any tone whatever 
between certain wide limits of absolute pitch. 
When the side apertures of the cavity were altered so as to suit it to the pro- 
duction of the vowel a’, the resonance rose in pitch ; and this was still more the 
case when the cavity was arranged for the vowel @. The highest proper tone 
(which for 6 was on /”) rose to ¢’”, and there was perceptible reinforcement as 
high ase”. In this case also the range of resonance was extensive, and was by 
no means confined to two or three tones. 
We now pass to the more general conclusions which we conceive may be 
drawn from our experiments. Ina letter which appeared in “ Nature,” No. 450, 
VOL. XXVIII. PART TII. 9P 
