INTENSITY OF THE VOICE. 463 



expired air is sent into the larynx by the muscles of expiration, that 

 the intrinsic muscles of the larynx give to the inferior ligaments suffi- 

 cient tension to divide the air, and that the air receives the vibrations, 

 whence sound results. The process is very complex. Before a single 

 word can be uttered, a series of actions must be executed: these, as 

 stated by Sir C. Bell, 1 consist in compression of the chest; adjustment 

 of the glottis; elevation and depression of the larynx, and contraction 

 of the pharynx, actions which will be readily understood after what 

 has been already said on the mechanism of phonation. 



1. Intensity or Strength of Voice. 



The strength of a sound depends upon the extent of the vibrations 

 of the body producing it. In the case of voice, it is dependent, in 

 part, on the force with which the air is sent from the lungs, and in part 

 on the size of the larynx. A strong, active person, with a capacious 

 chest and prominent pomum Adami, that is, with a large larynx, is of 

 an organization the most favourable for a strong voice. But if the 

 same individual, thus favourably organized, be reduced in strength, his 

 voice is enfeebled ; because, although the formation of the larynx may 

 be favourable, he is incapable of sending the air through it with suffi- 

 cient force to excite extensive vibrations of the vocal ligaments. 



The voice of the male is much stronger than that of the female, of 

 the eunuch, or child. This is greatly owing to his larynx being more 

 developed. The change in the voice of the male at puberty is owing to 

 the same cause, the prominence of the pomum Adami, which is first 

 observed at this age, indicating the elongation that has supervened in 

 the lips of the glottis. As voice is commonly produced, both ligaments 

 of the glottis participate; but if one should lose its power of vibrating, 

 from any cause, as from paralysis of one-half the body, the voice loses, 

 cseteris paribus, one-half its intensity. M. Magendie 2 affirms, that this 

 is manifested by cutting one of the recurrents on the dog. 



2. Tone of Voice. 



Nothing can exceed the human organ of voice in variety of tones, 

 and execution. Dr. Barclay has endeavoured to calculate the different 

 changes of which it is susceptible, proceeding on the principle, that 

 where a number of movable parts constitutes an organ destined for 

 some particular function, and this function is varied and modified by 

 every change in the relative situation of the movable parts, the number 

 of changes, producible in the organ, must at least equal the number of 

 muscles employed, together with all the combinations of which they are 

 capable. The muscles, proper to the five cartilages of the larynx, are 

 at least seven pairs; and fourteen muscles, that can act separately or 

 in pairs, in combination with the whole or with any two or more of the 

 rest, are estimated to be capable of producing upwards of sixteen 

 thousand different movements not reckoning as changes the various 

 degrees of force and velocity, with which they are brought into action. 



1 Philos. Transact, for 1832, p. 299; and Nervous System, 3d edit., Lond., 1837. 

 3 Precis, &c., i. 245. 



