作業者の聴力損失(PTS)の測定ならびにPTSと言語聴力障害との関連

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This study investigates the permanent threshold shift(PTS) of workers induced by industrial noise exposure and the relation between PTS and the impairment of speech perception. The results of the investigations and the experiments are as follows;1. Hearing thresholds of 510 noise-exposed workers and 325 subjects without noise exposure are measured. 2. Noise exposure of each worker is measured by means of indivifual noise dose meter which gives equivalent continuous A-Weighted Sound Pressure Level over the particular averaging time. 3. Articulations of monosyllabic words using the subjects having noise-induced PTS as well as normal subjects are measured. It is found that speech hearing test using monosyllabic words is not sensitive to hearing impairment. 4. Articulations of trisllabic words using the hearing impaired and normal subjects having NIPTS are measured in the presence of ambient noise and in the condition of reverberation. The results show that the hearing impaired are more imfluenced by reverberation in speech perception. 5. Digital filter simulating the recruitment phenomenon is programmed and distroted vocal sounds presumed the hearing impaired might hear are synthesized. 6. Articulations of monosyllabic sounds synthesized as above are measured using normal subjects and the result expressed as speech audiogramme are compared with that of the fearing impaired using notdistorted vocal sounds. The result shows that both audiogrammes are in satisfactory agreement.