1859.] on certain Auditory Phenomena. 6S 



conveying at the same time a major impression of the same sound to 

 the other ear : the sensation obtained through the latter ear totally 

 destroying or obliterating all sensation of the same sound in the other 

 ear. By the same sound is meant the sound proceeding from the same 

 body, as a watch, a bell, or from two bodies of the same kind, as two 

 tuning-forks of the same size and note. 



Major impressions on one earprevent sensations of minor impres- 

 sions on the other ear only in the case of the same sound, and not in 

 the case of sounds of a different character, unless indeed the major 

 sound happens to be very intense and deafening. Therefore the loud 

 sound of one watch and the weak sound of another watch may be 

 distinctly heard in the two ears, one in one ear only and the other in 

 the other ear only, provided that one ear be favoured with a major 

 impression of one watch, and the other ear be favoured with a major 

 impression of the sound of the other watch. In this case, the stronger 

 impression of either watch nullifies in a sensorial sense the weaker 

 impression ; and as the strong impression of one watch is made in one 

 ear, and the strong impression of the other watch is mad« upon the 

 other ear, one watch is heard in one ear and the other watch is heard 

 in the other. 



The principle of restriction of hearing of the same sound to that 

 ear on which a major impression is made is illustrated in respiration. 

 The ear connected with a part where the respiration is weak fails, as 

 has been already stated, to convey any sensation, while the ear con- 

 nected with a part where the respiration is strong produces sensation. 



The diagram represents the sounds occurring alternately in two 

 sides of the chest in a consumptive patient. The dark spots represent 

 the sounds. The right side has the Inspiration strong, the Expiration 

 laint. The left side has the Inspiration weak, the Expiration coarse. 



Healthy. Unhealthy. 



Right Side of Chest. Left Side of Chest. 



The same principle may be made to perform an important part in 

 the diagnosis of diseases of the heart, accompanied by murmur. If 

 the two cups of the stethophone be applied at two points of the area 

 of a murmur differing in intensity, the sound is heard by that ear only 

 connected with the point where the murmur is more intense. Now 

 as the source of a murmur is determined by the point of its greatest 

 intensity, it must be obvious that a ready mode of diagnosis is offered. 



Vol.111. (No. 29.) f 



