バンドノイズ及び純音による耳鳴マスキングレベルの比較検討

Abstract

The masking levels evaluated by band noise (band noise masking level: BNML) and by pure tones (pure tone masking level: PTML) at frequency of the pitch of tinnitus were compared in 343 tinnitus ears without hearing loss or associated with cochlear deafness whose pitch was identified by pure tones. The following results were obtained;1) The correlation coefficient between BNML and PTML was 0.80 when both masking levels were indicated by sensation level and it was 0.93 when they were indicated by audiometer level.2) The correlation coefficient between loudness and masking level was 0.53 in BNML and was 0.67 in PTML when both loudness and masking level were indicated by sensation level. It was 0.87 in BNML and 0.89 in PTML when both loudness and masking level were indicated by audiometer level.3) The regression line between loudness (x) and masking level (y) was calculated. It was y=0.67x+7.61 in BNML and y=0.90x+7.19 in PTML when both loudness and masking level were indicated by sensation level. It was y=0.85x+4.99 in BNML and y=0.88x+11.68 in PTML when both loudness and masking level were indicated by audiometer level.4) As far as the relationship between pure tone hearing level at frequency of the pitch of tinnitus and loudness, BNML and PTML was concerned, all loudness, BNML and PTML indicated by sensation level became small abruptly when the hearing level exceeded 25dB. However, the PTML indicated by audiometer level was minimally influenced by the hearing level at frequency of the pitch of tinnitus.5) The PTML indicated by audiometer level could be most useful as an indicator representing the intensity of tinnitus whose pitch was identified by pure tones.