498 VOICE AND SPEECH. 



A short time, however, after the laryngoscope came into use, 

 the larynx was examined during the production of vocal 

 sounds. The true value of previous theories was then 

 positively demonstrated ; and while it has not been possible 

 to settle all disputed points with regard to the precise mode 

 of action of certain muscles, the appearances of the larynx 

 itself during phonation and the results of the action of cer- 

 tain of the intrinsic muscles have been quite accurately 

 described. One of the first elaborate series of investigations 

 of the subject by means of tLje laryngoscope was made by 

 Manuel Garcia. 1 These observations were chiefly directed 

 to the changes of the glottis in singing, and were made by 

 Garcia upon his own person. The essential points devel- 

 oped by these experiments have since been confirmed by 

 Battaille, 2 and many other observers. 



Appearance of the Glottis during Ordinary Respiration. 

 If the glottis be examined with, the laryngoscope during 

 ordinary respiration, the wide opening of the chink during 

 inspiration, due to the action of the crico-arytenoid muscles, 

 can be observed without difficulty. This action is effected 

 by a separation of the posterior points of attachment of the 

 vocal chords to the arytenoid cartilages. During ordinary 

 expiration, none of the intrinsic muscles seem to act, and the 

 larynx is entirely passive ; while the air is gently forced out 

 by the elasticity of the lungs and of the thoracic walls. But 

 as soon as an effort is made to produce a vocal sound, the ap- 

 pearance of the glottis undergoes a remarkable change, and 

 becomes modified in the most varied and interesting man- 

 ner, with the different changes in pitch and intensity that 



with artificial vocal apparatus and with the larynx itself removed from the 

 body. Many of the ideas of Miiller have been carried out by recent laryn- 

 goscopic researches (Manuel de physiologic, Paris, 1851, p. 127, el seq.). 



1 GARCIA, Observations on the Human Voice. Proceedings of the Royal Society, 

 London, 1856, vol. vii., p. 399, et scq. 



2 BATTAILLE, Nouvellcs recherches sitr la phonation. Comptes rendus, Paris, 

 1861, tome Hi., p. 716, et scq. 



