408 THE VOICE 



or thick-register, while high liotes come from the high-, head-, or 

 small-register. The thin or middle register is used normally 

 by tenors and when the male voice sings falsetto. 



Laryngoscopical investigation has shown that, when producing 

 notes from the chest register, the glottis forms an elongated slit 

 and the vocal cords, stretched as tightly as possible, are vibrating 

 as thick masses over their w^hole extent. In taking the lowest 

 notes the posterior portion of the arytaenoid cartilages are close 

 together with a wide elliptical chink between the cords. As the 

 pitch of the note rises the arytaenoid cartilages are brought closer 

 together and so shortening of the vibrating portion of the cords 

 is produced. The thyreoid cartilage approximates to the cricoid, 

 and the vocal cords are stretched and brought close. The epiglottis 

 rises as the pitch rises. 



When the upper limit of this register has been reached the 

 tension on the various parts is extreme and one passes with relief 

 to the middle register — the normal mechanism in the female 

 (and tenors) for the production of notes between F3 and F4. 

 The thyreoid cartilage returns to its normal position, the tension 

 on the cords is decreased and they vibrate at their thin mem- 

 branous edges only. As the pitch rises the thyreoid and the 

 cricoid cartilages are again pulled together by the action of the 

 crico-thyreoid muscle, and this state of tension lasts in tenors, 

 sopranos and contraltos alike from F3 to C4. Higher notes than 

 this are attained by a shortening of the vocal chink. In the small- 

 or head-register the notes are produced by vibrations of only the 

 inner margins of the cords, and the vocal chink is reduced to a 

 small anterior aperture which becomes smaller as the pitch rises. 

 These different mechanisms produce tones of perceptibly different 

 quality (see Ear, Chap. XX.). 



If the intensity ranges of the ear are again referred to (Chap. XX.) 

 it will be seen that while the range of intensities covered by the 

 human ear is large, covering frequencies from 32 to 16,000 vibra- 

 tions per second, it is particularly sensitive to those frequencies 

 lying between 1,000 and 5,000 d.v. per second. In this middle 

 region it can pick up a pressure variation as small as one-thousand- 

 millionth of an atmosphere. Now, frequencies of this order occur 

 in phonation only in overtones. The main energy of the voice is 

 of much lower pitch. The male voice has a very pronounced low 

 component of about 120 d.v. per second, while the female voice 

 has one about an octave higher. About 60 per cent, of the energy 

 of the air emitted is due to vibrations having a frequency of less 

 than 600 d.v. per second. Under 5 per cent, of the energy is 

 associated with the production of overtones having a frequency of 



