Abstract
Directional hearing ability test is one of the essential methods in diagnosing retrocochlear deafness. A new directional hearing ability test apparatus, Model TD-01, has been used to test patients with unilateral hemicerebrum disorder due to cerebrovascular disorders such as cerebral hemorrhage and cerebral infarction. Testing was by a self-recording method, which is a modification of the manipulatory technique of a previous self-recording method, plus a conventional manual method and another self-recording method. This new apparatus produces time differences at random from a minimum of 2μsec to a maximum of 2 msec, without distortion, from an optional sound source. Compared with the conventional self-recording method, more precise judgement is now possible by the modified method we have devised to simplify the manipulation by the patient. The subjects were patients with hemiplegia in whom the disordered sites were distinguished by CT, etc., and whose symptoms were evident. For testing, they were divided into 27 cases for stage I and 27 for stage II . For comparison, a similar test was performed concurrently on normal subjects. The result: revealed significant differences between the left hemiplegia group, and the normal subjects, The self-recording method and the modified method were closely correlated in the left hemiplegia group, but not in the right hemiplegia group. From the results, the modifiec self-recording method was found to be more useful for judgement of derectional hearing ability in the hemiplegia patients tested, and the superior ability of the right hemicerebrurc to determine hearing direction was suggested by the larger number of cases in the left hemiplegia group in whom directional hearing ability was deteriorated.
