AIDS FOR THE DEAF

Hawke's Bay Herald-Tribune, Issue 107, 22 May 1937, Page 11

AIDS FOR THE DEAF

Efficacy of Instruments

Sound, the Cinderella of the physical •ciences, has only come dnto its own since the invention of the wireless valve, produced and developed under th# stimulus of broadcast engineering. It is now possible to measure the Tela-' tive intensity of sounds at various frequencies, and this technique, applied- " to the physiology of hearing, promises to euable ecientists and medical men to do a great deal more in future" to mitigate the disabxlities of the deaf, The Medical Besearch Council has published a reporfc of an investigation into the utility of hearing aids, and into n.ethods for determining what lypcs of instrument are best suited to partieu lar cases. The norma! human ear can apprehcnd sounds over an extraordintirily wide range tf intcnsities, from the scftest that can be heard in a still room to tho level at which sound be- , comes so lond that it bogins to produco physical discomfort. With dcaf people the softer sounds are not heard, but there appears. to be no corresponding cxtension of the upper limit. More-j over, the extemE of deafness may vaiy with the pitch (or frequency) of the sound. The piobiom is to devise an instrument wbich will bring the sounds

of human . speech within the narrowei' range of the deaf ' person 's liea*ing, either with as little distorthm as ro 3 sibie, or if recessary (on tho princip1.; of spectaclts) with a specific distor • tion caleuiated to compensato for an :rregular disaLvity. ' It is gatLered that this can be dona at least in pinciple. The investigation makcs- it clear that the valve types of hearing-aiid are Invariably better than other. kinds._ But they look forward to a time when the selling ofan aid will involvo as a matter of course a fcientific test of the deaf person 's' hearing and tho supply of an instrument spccially ad justed to the indiv'dual '?■' needs. They have worivcrt out a tec.Lnique for testing aitd proved its cfficacv over a large number of 'cases. They have some suggestions to make about the kind of apparatus most useful for teaching classes of deaf children^ where portability is not essential. Finally, they can flnd no evddence that the use of hearing-aids — Ithat is to say, habitually listening to speech which is amplified to a loudness approaching, but not exceeding the upper limit of the normal range — has any adverse effect on the hearing of oither deaf or normal ears. cessm emecessasmesssssssasa