VOICE AND SPEECH. 435 



fundamental note, or the rate of vibration to which it sympathetically responds, 

 varies accordingly. 1 That the resonance of the mouth cavity changes with 

 its shape is illustrated in the various pitch of the notes produced by Hipping 

 the edge of an incisor tooth, the cheek, or Adam's apple with the finger-nail, 

 while the mouth assumes the positions for production of the different vowels. 



Vowels whose normal pitch is low, as o, u, cannot be sounded easily in the 

 higher part of the musical scale; conversely, high-pitched vowels, as e in feet, 

 lose their character in the lower part of the scale. Language is, therefore, 

 much less distinct in song than in speech. 2 



It has already been stated that the difference in quality of musical notes 

 depends upon the number and relative intensity of their partial tones, each 

 of which is separated from the fundamental tone by a fixed interval. Since 

 the mouth parts have a fairly fixed position for each vowel sound, the buccal 

 cavity reinforces by sympathetic resonance tones of definite vibration rates. 

 When a given vowel is sounded in different parts of the musical scale, now 

 one, now another partial tone is reinforced, according as its pitch harmonizes 

 with the prime tone of the mouth cavity, so that the interval between the 

 resonated partials and their fundamental tone may change, with corre- 

 sponding change in the quality of the vowel sound. That is, the resonated 

 partial depends not only on its relation to the fundamental, but also on its 

 vibration rate. 3 This feature of vocal resonance distinguishes the human 

 larynx from most musical instruments. That the ground is not covered by 

 these facts was shown by Auerbach, 4 who demonstrated that the strength of 

 upper partials in vowel sounds depends also on the strength of their production 

 by the vocal cords and, therefore, upon their relation to the fundamental tone. 

 That is to say, the quality of a vowel is dependent not only on the absolute 

 vibration numbers of its upper partials, according to which they are or are not 

 reinforced by the position of the mouth, but also on the relative position of these 

 upper partials as compared with the fundamental tone. 



The peculiar aesthetic value of the human voice is dependent on the fact 

 that, on account of its varied powers of adjustment, the larynx is capable of pro- 

 ducing many more kinds of tone-quality than any artificial instrument. Helm- 

 holtz 5 found no less than sixteen overtones to accompany the fundamental. 



The posture of the mouth-parts differs markedly when set for the various 

 principal vowel sounds ; but as we know that each vowel sound has several 

 modifications or gradations so that a tone may pass by an easy glide from one 

 to another, so the form of the mouth passes by insensible steps from one vowel 

 position to another. It will be seen later that several articulate sounds play 

 the part now of vowels, now of consonants, according to their position in the 

 syllable or mode of formation. There has also been shown reason lor believ- 

 ing that the form of the chest cavity and the tension of its walls arc factors in 

 determining the pitch of its fundamental tone; so that through the varied 



1 Helmholtz: op. cit., p. 108. ' l Op. cil., p. 114. 3 Op. cit., p. 118. 



4 Quoted by Griitzner: op. cit., p. 179. 5 Op. cil., p. 103. 



