余の語音明瞭度曲線による聽覺檢査法

　1．緒論

　聽覚檢査法もこの世紀に入つてから可成りの進歩を遂げて來た．特にこの20数年電氣音響学の長足の進展は目覚しく，眞空管を利用した器械は耳科学方面にも取入れられ．アメリカに於ける各種のAudiometerや独逸のOtoaudionの諸型等は代表的のものである．然るに我國では之等の器械が充分に消化され普及するに至らぬ前に戰時体制となり，この方面の研究は立遅れてしまつた．然しそれ等の器械は純音の系統的，或いは連続的発生裝置であり，ただ任意の強度を持続或いは変更せしめ得る便はあるが質的には先ず優秀な音叉を以て代用し得るのである．

　他方言語を使用する檢査法に関しては主として咡語により單語等を発し，之を聽取せしめる場合の聽取最大距離を測定する方法が專ら行われて來た．この咡語檢査の基本となる諸要項の知見については古くはOskar Wolf（1871）が実に根氣のよい精密な業績を残しているし，その後にBezold，Bárány，Lampert或いは我國では園田・増田の研究等が出て詳細に檢討されて來た．けれどもそれ等の方法は距離の変更を以て音の減衰を図るやり方に於て殆んど変りはない．之には幾多の問題があり欠陷も数えられる．尤も單語と言つてもWechsellautmethodeの如く相当に語音の性質を究めた方法もある．之には音声学，心理学及び音響学の諸問題が錯綜して來る可能性もあろう．

Kawada devises a new method in testing the hard of hearing by use of articulation curve in which the results are far more revealing of ac-tual state of the patients than the mathod that had been employed préviously. Instead of depe-nding upon changes in hearing distances for varied intensities as measurement of hearing the whispered words, two separate sound-proof roo-ms are constructed, one of which is used for transmitting and the other for recliving, and, mutually connected with each other with a met-al tube 5 cm in diameter. On the transmitting end is placed a specially constructed attenuator by application of phenomenon of sound absorption capable of producing 16 levels of attenuations; a list of monosyllable words chosen at random is read first, in whispered voice and then, in speech voice with same intensity throughout the test; and thus possible changes in the articulation is measured. The clarity of articulation in relation to loudness of the sound is obtained by testing upon a normal person and recorded on a graph which is called the normal articulation curve. Articu-lation curve of the hard of hearing is obtained in the same way and compared to the normal curve.