The finding of diplacusis in a case of deafness is a valuable diagnostic aid in localizing the pathologic condition, since diplacusis can be caused only by a lesion of the organ of Corti. This statement is based on theoretic considerations, which I shall discuss, and on clinical observations, which I shall describe. If it is true, some practical applications follow for the diagnosis and treatment of certain cases of deafness and of M\l=e'\ni\l=e'\re's syndrome.
INTRODUCTORY OBSERVATIONSDefinition.\p=m-\diplacusis is the hearing of one sound as two. There are three varieties of diplacusis : Diplacusis binauralis echotica, in which a sound is heard a fraction of a second later by one ear than by the 1. Schilling, R.: Ueber musikalisches Falschh\l=o"\ren,Arch. f.