THE VALUE OF ROUTINE IN-THE-EAR MEASUREMENT OF HEARING-AID GAIN

When selecting the frequency response of a hearing aid, a target is us ually selected using a predictive formula from the international liter ature. Nowadays real ear measurements can readily be carried out to en sure that the real ear gain closely matches the prescribed target. Suc h measurements are usually only carried out on a subset of patients fi tted in the UK, though it has been suggested that they should be carri ed out on all hearing aid prescriptions. Real ear insertion gains were measured on 319 first-time National Health Service (NHS) hearing aid issues. A total of 181 (57%) failed to come within 10 dB of the target gain at one or more frequencies between 0.25 and 3 kHz. Though there were audiometric differences between those who achieved satisfactory g ain and those who did not, there was too much overlap between groups t o make any audiometric index or combination of indices of value in pre dicting the likelihood of failure to achieve target gain. Sixty-eight patients with inadequate real ear gain were invited to attend for alte rations to their hearing aid prescription. Twelve (18%) were fitted wi th a high frequency aid, while the rest were managed by alterations to their NHS aid or to the earmould and tubing. After appropriate change s, 58 (85%) achieved a satisfactory gain. The routine use of real ear insertion gains in all hearing aid fittings would result in many patie nts having a more accurately fitted hearing aid. As the majority of pr escriptions could be adequately improved using NHS hearing aids, the e ffects on the hearing aid budget would be relatively small.