再び高校生にみられる高音障害型感音難聴について

High Frequency Sensorineural Hearing Impairment among Senior High-School Students

　I．緒言

　筆者は前報^4）において，高校生の主として男性にC⁵-dip，C⁵，C⁶障害など，慢性騒音性難聴を思わせる高音障害型感音難聴のあることを見出し，原因については，最終的な断定はできないが，音楽聴取，特にヘッドホン，イヤホン^＊＊の使用および，音響刺激に対する受傷性の個体差が発生の最も疑わしい要因と推定した。この報告に対しては，その後若干の批判があったが，要約すると，次の2項目になる。

　1）上記の高校生の難聴というのは，高校生になって初発したものではなく，何等かの原因により，もっと年少の頃から存在していたものではないか。

　Screening test for hearing was performed in senior high-schools in 1980, and 66 students had abnormal hearing. Among them 39 students (M. 31, F. 8) were referred to our hospital, and the further audiometric studies of 29 students (M. 26, F. 3) showed high frequency sensorineural hearing loss. It was found that senior high-school students have high incidence of hearing loss and high sex ratio (M/F) in comparison with elementary and junior high-school students.

　Seventy per cents of hearing-impaired students selected at screening test in senior high-schools were first pointed out their hearing loss after they entered to the senior high-schools. Among all students 45.8% male and 19.5% female were using head-phone and earphone, and among the 29 hearing-impaired students 76.9% male and 33.3% female were using them.

　The high frequency hearing impairment among senior high-school male students could be due to noise environments including the use of headphone and earphone, and to the individual vulnerability to acoustic stimulus.