Evaluation of Hearing Aid Fittings for Infants

Studies were conducted of a method for evaluating hearing aids fitted to children. The procedure, a modification of that suggested by Gengel, Pascoe and Shore (1971), involved comparing the aided thresholds at a number of frequencies with the levels of the corresponding frequency bands of a speech signal, and from this, calculating the sensation levels at which various parts of a speech signal would be received. In the first study of 182 hearing-impaired children it was found that the sensation levels received through hearing aids at preferred volume setting were inversely related to hearing levels. This indicated the need to consider hearing levels when estimating the sensation levels which are likely to be tolerated. It also emphasised the difficulty of providing useful sensation levels at frequencies where hearing level was extreme (over 100dB). A second study showed little agreement between the aided sensation levels obtained by testing hearing-impaired children and parents’ reports of aided hearing adequacy. One reason for this disagreement appeared to be lack of objectivity in some of the parents’ reports. A series of case studies illustrated various applications of the evaluation procedure. It was demonstrated that by using a C.O.R. technique the procedure could be used even with infants. This was considered especially important in view of the desirability of providing optimum amplification for hearing-impaired children as early in life as possible.