Visual Aid in the Oral Teaching of Deaf Mutes

PROBABLY every one is acquainted with Kœnig's manometric capsules and revolving mirrors, and it occurred to me that I might help a deaf mute to learn inflection in speaking by his imitating the curves produced by my voice in the mirrors. For this purpose I arranged two capsules with oblique membranes and small diameter side by side, one being higher than the other, so that two bands of flame half inch wide, and half inch apart, appeared in the revolving mirrors. The capsules were tuned alike, and furnished with tubes and conical mouthpieces; through one of these I made the sound of a note, vowel, or syllable in various pitches, and my friend endeavoured to imitate through the other tube the curve in the flame band produced by my voice. As an experiment the results were quite satisfactory, for before an hour was over he could imitate a range of nearly an octave, and would tell me correctly, through watching the curves of flame, when the note he uttered was like mine. I am not interested in the oral teaching of the deaf, but having frequently to use Kœnig's invention, I think the principle might be made useful to oral teachers. My friend, upon whom I experimented, is said to have been well taught, his age about twenty years, but his voice (?) is a hoarse monotone.