

VOICE AND SPEECH 623 



be seen to vibrate over their whole extent. When singing with the head voice, 

 the vibrations of the cord are apparently confined to their inner margins ; 

 the aperture of the glottis is wider in front than behind, so that more air 

 escapes during phonation by this method than in the production of the 

 chest voice. 



In order to change the pitch of the note the following means are probably 

 employed in the larynx : 



(1) Alteration in the tension of the vocal cords. 



(2) Alteration in the length of the part of the vocal cords that is 

 free to vibrate, which can be accomplished by the approximation of the 

 arytenoid cartilages to one another, or by their approximation to the thyroid 

 cartilage. 



(3) The alteration in the shape of the vocal cords, which is determined by 

 the activity of the different portions of the internal thyro-arytenoid muscles. 



(4) The varying pressure of the blast of air passing through the glottis. 

 The loudness of the tone produced is practically proportional to the 



force of the blast of air employed. The quality or timbre of the voice 

 depends not so much on the vocal cords as on the accessory resonating 

 apparatus, represented by the trachea and chest and by the cavuVes of the 

 mouth and nose. The greater part of the education involved in voice training 

 is directed to the modification of the shape of the mouth cavity, so as to 

 secure the greatest possible fulness, i.e. richness in overtones, of the tone 

 produced in the larynx. 



THE MECHANISM OF SPEECH 



The sounds employed in speech, viz. vowels and consonants, are produced 

 by modifying the laryngeal tones by changes in the shape of the mouth and 

 nasal cavities. In whispering speech there is no phonation at all, but the 

 sound is produced by the issue of a blast of air through a narrow opening 

 between the lips, between the tongue and soft palate, or between the tongue 

 and the teeth. JM 



VOWEL SOUNDS are continuous, whereas the consonants are pro- 

 duced by interruptions, more or less complete, of the outflowing 

 air in different situations. The simple vowel sounds, U, 0, A, 

 E I, (pronounced as in Italian oo, oh, ah, eh, ee), are tones, 

 i.e. are produced by a regular series of vibrations. These tones 

 take their origin in the mouth cavity, as can be shown easily by the fact 

 that we can whisper these sounds distinctly without any phonation what- 

 ever. To each of them corresponds one or two distinct notes, the pitch, i.e. 

 the resonance, of which is regulated by the shape of the cavity in which 

 they are produced. There has been much controversy as to whether the 

 pitch of these notes changes at all with the pitch of the voice, or varies 

 in different individuals. Some said that they did not change, others that 

 their pitch kept in constant ratio with the pitch of the note sung : if the note 

 doubled in pitch, so also did that (or those in the case of E and I) of the vowel. 

 Several methods have been employed for investigating this point : 



