RESPIRATION 285 



not act as a mere resonator, but that for each vowel, in addition to 

 the fundamental note due to the vibration of the vocal cords, the 

 pitch of which is, of course, variable, one or, it may be, two other 

 notes (formants, as he calls them), not necessarily harmonics of the 

 laryngeal note, but separated from it by a constant or nearly con- 

 stant musical interval, are directly produced by the passage of the 

 regularly interrupted expiratory blast through the mouth, the air 

 contained in that cavity being for an instant set into vibration at 

 each interruption. On this view it is the musical effect produced 

 by the oscillation or continual recurrence, in short series, of these 

 vibrations which gives the vowels their quality. The fact that it 

 is by no means difficult to sing (with the larynx) and whistle (with 

 the mouth) at the same time, shows the possibility of Hermann's 

 view, that a fixed tone can be generated in the mouth by the inter- 

 mittent stream of air issuing from between the vibrating vocal cords, 

 just as a tone is gensrated in a pipe by blowing into or over it, and 

 his records do show continually recurring groups of vibrations as 

 his theory requires. McKendrick takes up a middle position, 

 believing that both theories are partially true, and this seems to 

 be the best conclusion which can at present be arrived at. It 

 seems clear, at any rate, that more than one factor is concerned in 

 the timbre of the vowel sounds. 



When the vowels are being uttered, the soft palate closes the 

 entrance to the nasal chambers completely, as may be shown 

 by holding a candle in front of the nose, or trying to inject water 

 through the nares. If the cavities of the nose are not completely 

 blocked off, the voice assumes a nasal character in pronouncing 

 certain of the vowels ; and in some languages this is the ordinary 

 and correct pronunciation. 



Many animals have the power of emitting articulated sounds ; 

 a few have risen, like man, to the dignity of sentences, but these 

 only by imitation of the human voice. Both vowels and conr 

 sonants can be distinguished in the notes of birds, the vocal 

 powers of which are in general higher than those of mammalian 

 animals. The latter, as a rule, produce only vowels, though 

 some are able to form consonants too. 



The nervous mechanism of voice and speech will have to 

 be again considered when we come to study the physiology of 

 the brain and spinal cord. But the curious physiological anti- 

 thesis between the functions of abduction and of adduction of 

 the vocal cords may be mentioned here. The abductor muscles 

 are not employed in the production of voice ; they are associated 

 with the less specialized, the less skilled and purposive function 

 of respiration. The adductor muscles are not brought into 

 action in respiration ; they are associated with the highly- 

 specialized function of speech. Corresponding to this difference 

 ol function, we find that adduction is preponderatingly re- 

 presented in the cortex of the brain, abduction in the medulla 

 oblongata. Stimulation of an area in the lower part of the 



