Abstract
The testing described was made with a selection of pupils 8–11 years of age in a school for deaf and profoundly hard-of-hearing children. The object was to compare the effect of the “Phonic Ear” HC 229 hearing aid with the effect of the hearing aids so far used by the children. With a view to avoiding to the greatest possible extent any influence by irrelevant factors the testing was carried out as double-blind determinations, i.e. control (“dummy”) hearing aids were made with the same appearance as that of the HC 229 aid, but with the same acoustic properties as those of the pupils' own hearing aids. Statistically the testing did not show any significant difference between the results obtained with HC229 aids and those obtained with the “dummy” aids, but a detailed study of the results gives an indication of slightly better speech audiometry results with the HC229 aid, and this finding ought to be further investigated. Any expectations that it should be possible to achieve dramatic improvements of discrimination, sound attention, and speech in the course of a training period of a few months' duration by switching over to HC229 have been invalidated as far as 8–11-year-old pupils with audiogrammes as indicated are concerned.