Researches in expermental phonetics. 
89 
Of all the methods and investigations employed for determining the 
mouth tone those of Hermann1 are entitled to by far the weightiest con¬ 
sideration. He finds for u (00) two tones, one in the first part of the 
first octave and one in the second octave, for o (au), and a a tone in the 
second octave which rises in pitch as 0 changes to a, for ä and ë a tone in 
the second octave and one in the third octave, for Ö, ü and i a very high 
tone which is in the middle of the third octave for ö, at the end of that 
octave for ü and in the fourth octave for i. The octaves are numbered in 
the German fashion, middle c being in the first octave. The resonance 
tones for my examples of a and i are given on pages 55 and 56, and those 
of some other vowels in Section III. 
These data give only the approximate regions in which we may expect 
to find the mouth tone. It is unquestionably true that within these regions 
the mouth tone will vary for different dialects and different conditions of 
speech. 
The mouth tone need not be a fixed one though it is generally so. A 
rise and fall of the mouth tone might readily be used as a factor of ex¬ 
pression in speech. Several examples of such changes have been given 
in Section II. 
It seems fairly well established that in addition to the cord tone there 
may be several resonance tones from the mouth cavity. Lloyd dis¬ 
tinguishes at least two : that of the front part of the mouth (the porch 
resonance) and that of the whole mouth (the fundamental resonance).2 
There may be also a resonance tone from the pharynx.8 The various 
vowels arise from different “radical ratios’’ between the porch tone 
and the fundamental mouth tone,4 5 while it is possible to change the 
pitch of both to some extent. Various other tones may arise from the 
configuration of the mouth and the coexistence of the tones already 
mentioned.8 
Although Lloyd’s supposition of the possible presence of a number of 
resonances in the mouth cavity6 * may be partly justified, yet one of these 
resonances must far exceed all others in prominence in order to produce 
the constancy in form and period of the resonance vibrations seen in the 
'Hermann, Phonophotographische Untersuchungen, Arch. f. d. ges. Physiol. (Pflü¬ 
ger), 1894 LVIII 270. 
2 Lloyd, Speech sounds ; their nature and causation, Phonet. Stud., 1890 III 261. 
3 Lloyd, Speech sounds ; their nature and causation, Phonet. Studien, 1891 IV 294 ! 
also a note in Proc. Brit. Assoc., 1891 p. 796. 
'Lloyd, Speech sounds ; their nature and causation, Phonet. Stud., 1891 IV 52. 
5 Same, 207. 
6 Lloyd, Speech sounds ; their nature and causation, Phonet. Stud., 1890 III 261; 
1891 IV 52, 206.