550 



VOICE AND SPEECH 



and sensory centers. Thus, the production of coordinate vocal sounds 

 is really a distinguishing characteristic of man; no other animal can 

 at all equal his power of phonation.^ Some seemingly authentic 

 cases, however, are on record which show that speech of a very crude 

 and hmited type may also be acquired by other mammals, and (^uite 

 aside from the *' talking horse" and "talking dog," it seems that the 

 monkeys and apes have a limited register of words, conveying different 

 meanings. 



The Examination of the Lar3mx in Reflected Light. ^ — In animals 

 the play of the laryngeal parts may be studied without much difficulty 

 by direct inspection. A transverse incision having been made between 

 the hyoid bone and the upper edge of the thyroid cartilage, the larynx 

 is raised upward and tilted sufficiently to allow an unobstructed view 



Lamp 



Larynx. 



Fig. 272. — Diaqrajh of Laryngoscope. {From Stewart's "A Manual of Physiology," 

 William Wood and Co., Publishers.) 



of the supraglottic cavity and especially of its floor formed by the 

 vocal cords. Killian^ has devised a method of transillumination 

 by means of which the larynx may be projected in magnified form 

 upon a screen. The human larynx may be inspected with the help of a 

 small plane mirror which is mounted upon a handle and is placed ob- 

 liquely against the uvula. A beam of light is then reflected upon it 

 from a head mirror (Fig. 272). The observer looking through a small 

 central opening in the latter, obtains an image of the parts below, but 

 those normally situated in front, appear in the picture to be located 

 behind, and vice versa. 



The white glistening vocal cords are sharply outUned against the 

 red mucous Uning of the rest of the laryngeal wall (Fig. 268). During 



^ Mott: The brain and the voice in speech and song, New York, 1910, and 

 Aikin, The voice, an introduction to practical phonology, London, 1910. 



2 First successfully undertaken in 1854 by M. Garcia, a teacher of singing. 

 In 1857 Tiirck employed this method upon his patients in Vienna. 



3 Miinchener klin. Wochenschr., No. 6, 1893. 



