Abstract
i) Using an electro-mechanical switch, we delivered speech alternately to both ears. Subjects who were tested were a group of 35 normal young adults and a group of 39 healthy older individuals.
Methods of examination were as follows ;
A. Monaural discrimination of mechanically resynthesized interrupted speech.
B. Binaural discrimination with aural alternation of stimuli.
C. Monaural discrimination of interrupted speech.
i) The relationship between interrupted frequency rate and speech discrimination for monaural and binaural alternating hearing was investigated.
In case of monaural hearing, the higher the rate of interruption, the better the disrimination ; however, in case of binaural, the discrimination was constant regardless of interruption frequency.
iii) When interrupted speech is introduced into one ear or alternatively introduced into both ears, the discrimination score of the aged lowered compared with the young adults.
iv) Analyzing the confusion matrix of speech discrimination, we divided the central mechanism of binaural hearing, i. e., binaural summation of hearing, into two parts ; pseudo- and real summation of binaural hearing. In advanced age, the part of real summation decreased.
v) As for the clinical application of interrupted speech, the diagnostic values of the central deafness and of the malingering of unilateral deafness were discussed.
