On temporal characteristics in hard-of-hearing persons

It is difficult to obtain sufficient speech articulation even if the amplified sound is given to the sensory-neural hearing impaired persons. It is conceivable that one of the reasons is that the temporal resolution of the auditory sense is low. In this paper, the temporal resolution of two short sounds and a temporal masking characteristic were investigated, targeting the hearing impaired students who belonged to the school for the deaf. As a result, an auditory image that was produced by a short sound could be apporoximated with a normal distribution function and a forward masking curve could be apporoximated with the exponential function. The temporal characteristic of the auditory sense was evaluated by using parameters of these functions and the parameters were compared with those of the normal hearing listeners. Although the 2-sound temporal resolution of the hearing impaired was almost the same as that of the normal listeners, the range of forward masking of the hearing impaired spreaded 3-4 times compared with normal persons. As for the range of backward masking, there was no difference from normal persons. How to design the hearing aid for the sensoryneural hearing impaired was discussed on the basis of these results.