618 COMPARATIVE. HISTORICAL. 



Incomplete, unilateral paralysis of the recurrent laryngeal nerve results at 

 times in double tone (diphthongia) of the voice, on account of the unequal tension 

 of the two vocal bands. According to Tiirck and Schnitzler, diphthongia may 

 develop also when the vocal bands are in contact at one point in their course 

 (perhaps by reason of deposits or tumors) , so that the glottis is divided into two 

 sections, each of which produces the sound of the voice in a different pitch. If 

 the glottis is suddenly closed by muscular spasm while the voice is being sounded, 

 the rare condition of spastic aphonia results. In tabetic patients ataxic phenom- 

 ena have been observed occasionally in the laryngeal musculature. Hoarseness is 

 caused by accumulation of mucus on the vocal bands, or by roughness, swelling, 

 or relaxation of the bands. If the bands suddenly come in contact while closely 

 approximated during speaking, the voice "breaks," on account of the formation 

 of nodal points. 



Diseases of the pharynx, nasopharynx, and uvula may cause reflex nervous 

 disturbances of the voice. 



The reestablishment of audible voice and speech has been observed even 

 after total extirpation of the larynx, the individual breathing through a tracheal 

 tube and no air escaping through the cavity of the mouth. The subject under 

 such circumstances fills with air the cavity left by the removal of the larynx, 

 and forces the air through a narrowed space above into the cavity of the mouth, 

 thus producing a monotonous sound of stenosis that is remarkably like the voice. 



Paralysis of the soft palate, as well as perforation or congenital fissure, gives 

 a nasal timbre to all vowels; the former also causes difficulty in the normal forma- 

 tion of consonants of the third articulation-position. The resonants are well 

 marked, while the explosives are enfeebled, on account of the escape of air through 

 the nose. 



Paralysis of the tongue causes difficulty in the pronunciation of I (ee) ; E (a) , 

 and A (ah) also are less easily pronounced. In addition, the formation of con- 

 sonants of the second and third articulation-positions is disturbed. However, 

 persons having even considerable defects of the tongue have reacquired intelligible 

 speech. Aphthongia is that condition in which each attempt to speak results 

 in spasmodic movements of the tongue. 



In the presence of paralysis of the lips (facial nerve) the extent to which the 

 consonants of the first articulation-position can be pronounced should be observed. 

 Hare-lip also must be taken into consideration in this connection. In case of nasal 

 obstruction speech assumes the so-called "obstructed oral tone." The formation of 

 the resonants in the normal way is prevented. After extirpation of the larynx, 

 an artificial larynx has been inserted between the trachea and the mouth, con- 

 sisting of a metallic reed in a tube. All disturbances in the formation of conso- 

 nants may be designated as "stammering" (dysarthria litteralis). Speech-de- 

 rangements of cerebral origin are considered on p. 796. 



COMPARATIVE. HISTORICAL. 



Speech may be included among the "movements of expression." Psychic 

 excitement arouses in man characteristic movements, in which special groups of 

 muscles constantly participate ; for example laughing, crying, facial expression, and 

 gestures in fear, anger, shame, discouragement, ambition, disgust, abhorrence, desire, 

 joy, merriment, etc. Such movements constitute a medium by means of which 

 related beings are enabled to communicate their inner thoughts to one another. 

 In their origin these movements of expression are reflex motor phenomena; but 

 when reproduced for purposes of explanation, they are voluntary imitations of 

 these reflexes. In addition to emotional movements, impressions on the sense- 

 organs also call forth characteristic reflexes, which are converted into movements 

 of expression; for example, stroking or painful stimulation of the skin, movements 

 following the perception of pleasant or unpleasant odors, likewise the influence 

 of sound, also of light (bright or dark, and of colors), and the perception of objects 

 of all kinds. 



In their simplest form movements of expression are manifested in sign- 

 language. In a narrower sense speech may be designated as "sound-pantomime," 

 the accompanying motor phenomena often taking the form of facial expression 

 and gesture. Thus, articulate sound is caused, in the first place, by characteristic, 

 reflex motor 'phenomena in the speech-forming organs. 



A second means of expression lies in the imitation of sound-phenomena by 



