Abstract
On the basis of normal hearing, speech hearing about discrimination loss and mishearing of speech sound in conductive and perceptive deafness was observed clinically in connection with pure tone hearing. The result was as follows:
It was presumed that speech hearing of impaired ear was considerably influenced by distortion of the frequency showing the form of air conduction curve on pure tone audiogram.
Therefore, in order to detect this cause, the author made an audio-frequency charachteristics altering device which acted as a sharp cut off high pass filter at 250 500 1000 2000cps, broad cut off high pass filter, sharp cut off low pass filter at 4000 2000 1000 500cps and broad cut off low pass filter.
And, then, speech hearing of impaired ear in which the air conduction curve showed abrupt and, gradual form of high tone deafness and gradual form of low tone deafness was compared with that of normal ears with the tone experimentally distorted.
The result was as follows:
It was recognized that speech hearing of impaired ear was similar to that of normal ears with experimental distortion.
Accordingly. it was considered that the distortion of the air conduction curve with pure tone audiogram was one of the important factors to influence on the speech hearing of the impaired ear.
