Wm. J. Kerr 273 



evenly to the sides of the larynx and at other points equidistant from the 

 larynx, as shown in figme ii, the paralyzed vocal cord can be readily deter- 

 mined. The sounds are of greater intensity on the side on which the vocal cord 

 is intact while the paralyzed cord is incapable of producing a normal sound. 

 The sound used for the determination is repetition of a high-pitched tone 

 and may be produced by having the subject pronounce the long letters E or A. 

 In a large number of patients who had paralysis of one vocal cord due to 

 goiter with associated injury of the laryngeal nerves or due to aneurysm of the 

 aorta with associated injury of the left recurrent laryngeal nerve, we have 

 been able to discover the site of the paralysis. In some of these patients direct 

 laryngeal examination of the vocal cords had given doubtful evidence of the 

 paralysis. 



Ajitrum of Highmore. If one antrum of Highmore is filled with fluid, the 

 nasal tones do not reverberate over it as well as they do over the unaffected 

 sinus. The symballophone is useful in detecting this abnormal state. The 

 physician stands directly behind the patient and while he applies the chest 

 pieces evenly over the antra the patient repeats "ninety-nine," "nine unknown 

 men," or some other combination of nasal tones. The louder sound is lateral- 

 ized to the side of the normal antrum. 



Malingerers of Hearing may be discovered by use of the symballophone. In 

 this instance the earpieces are inserted in the patient's ears. After he has been 

 blindfolded, sounds are made by the physician over either chest piece. If the 

 hearing in one ear is very defective, the sounds that arise in either chest piece 

 are referred to the ear with normal hearing. By alternately clamping the rub- 

 ber tubing in the headset of the instrument, sounds may be deflected to either 

 ear. Thus it is impossible for the malingerer to escape detection. 



Joints and Muscles. By means of the symballophone, sounds in paired joints 

 in motion may be compared. This method is particularly useful in the study 

 of the tempero-mandibular joint. Uneven mastication may resiUt in injury 

 to one joint. Faulty or uneven movements and abnormal sounds may be noted 

 and lateralized. Differences in the time when events occur in the joint can 

 be readily determined. In studying paired muscles with the symballophone, 

 the impaired sound may be detected on the affected side by comparing 

 the purring sounds produced when the muscles are stretched or contracted. 

 This observation may be important when slight differences occur in the mus- 

 cles of the two sides of the body, as in minor degrees of paralysis or in residual 

 weakness on one side following hemiplegia or monoplegia which is too slight 

 to be detected by ordinary means. 



Stomach and Intestine. Peristaltic sounds in the stomach and large bowel 

 may be studied by the use of the symballophone. It may be important to de- 

 termine whether peristaltic sounds in the epigastrium are moving from left 

 to right or from right to left. The former would suggest that the sounds arose 

 in the stomach; the latter, that they arose in the transverse colon. 



The symballophone is of no value to persons whose hearing is defective in 



