THE PRODUCTION OF THE VOICE 325 



internal pressure upon the membrane, and thus precludes ac- 

 cidents which would otherwise interfere with its proper vi- 

 bration. 



The auditory center in man is in the first and second tem- 

 poral convolution of the temporo-sphenoidal lobe. 



Briefly then, the physiology of hearing is as follows: 

 Sound waves collected by the pinna enter the external audi- 

 tory canal and impinge upon the membrana tympani. The 

 drum is thus set to vibrating and communicates its move- 

 ments to the ossicles, which in turn hand them over through 

 the fenestra ovalis to the fluids of the internal ear, through 

 which media they reach the auditory filaments, are conducted 

 to the brain and given proper recognition. 



The Production of the Voice. 



The production of the voice is not connected with the spe- 

 cial senses, but its consideration will be introduced here for 

 the sake of convenience. 



The Larynx is the organ of voice. It is a cavity closed 

 except for its openings above and below. It consists of four 

 cartilages cricoid, thyroid and two arytenoid joined to- 

 gether by ligaments and muscles. The vocal cords are at- 

 tached posteriorly to the bases of the movable arytenoid car- 

 tilages and anteriorly to the angle between the alae of the thy- 

 roid. The muscles serve to move the cartilages and thus to 

 separate or approximate and to render lax or tense the vocal 

 cords. 



Production of Sound. The human voice is produced by 

 vibrations of the vocal cords, which vibrations are set up by 

 currents of expired air. 



Movements of the Vocal Cords. These are those taking 

 place (i) in respiration, and (2) during vocalization. 



i. In Respiration. When the cords are "passive" they are 

 approximated anteriorly and separated posteriorly, so that 

 the interval between them (rima glottidis) is triangular. This 



