気導閾値変動の統計的観察

　I．緒言

　聴力検査としてのAudiometryにも種々の欠点はあるがCollege of Physicians and Surgeons Columbia UniversityのOtolaryngologyのDepartmentで確立された如く，PureTone Audiometryを除いてはHearing Capacityのacurate Testはなく検査範囲の広い点でも第一である。然し感覚を対象とする以上種々の心理的因子によつても影響は免れ難い。最も必要な最小可聴閾値測定に於ても20db以内の生理的動揺範囲が認められている如く，最小可聴閾値を点として決定することは困難である。正常人気導閾値動揺に関する報告は少なくないが難聴者に対しては僅かに大和田，立木等のそれがあるに過ぎない。よつて私は東京労災病院に於ける臨床検査成績よりDetaを整理し御批判を乞う次第である。なお便宜上変動とは主として好転（訓練効果）或は悪化の如き一定方向への偏位を，動揺とは不特定方向への偏差という意味に解して記述した。

The changes occurring in the air-conducted hearing threshold upon tests that may be performed either continuosly or periodically are observed in 29 ears, normal hearing, 16 ears, special. hearing tests, 509 ears affected with trumatic head injury occupational dea-fnessetc. All tests are performed in a sound-proof room.

The threshold changes appeared to be the greatest in the region of high-tone ; the least in the middle-tone. The amount of changes became small after the second trial of the repeated tests but it was rather large com-paratively in the region of the low-tone.

The threshold changes occurring among youg women of normal hearing upon repea-ted-tests were considerable but such changes appeared to be less when compared to similar tests made on other patients in general.

Aside from the results of periodic tests ma-de on the group of occupationally deaf repeated tests showed the effect of training. When the results of continual and periodic tests were compared to each other, the effects of training were shown more in the former while changes in the threshold value appeared to be emphasized more in the latter.

Worsening effects of average threshold value were shown in the group who were affected with occupational deafness and appeared to be the more marked among the aged that seemed to be related to T. T. S. and definitely specific for this condition.

The group requiring special hearing tests compared with those who received traumatic head injury ; among them the average thre-shold changes appeared to be the more or less similar and small in degree.