Evaluation of initial fittings of hearing aids with real ear measurement

ABSTRACT Objective: It was aimed to evaluate the amount of obtaining the target gains of hearing aids (HAs) at their initial fittings by means of real ear insertion gain (REIG) scores. Material and Method: Twenty-four adults (12 women and 12 men) whose otoscopic examination was normal and had no middle ear pathology were includeding in to the study. In the study, two premium segment digital behind the ear hearing aids belonging to different brands were compared. Factors such as ear mold, ventilation diameter, sound tube, hearing threshold, initial fittings, and gain formula, which affects the REIG were fixed. NAL-NL2 was preferred as the gain formula. REIG scores were measured at the frequencies of 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4 and 6 kHz using the International Speech Test Signal (ISTS) at 55, 65 and 75 dB SPL intensities. REIG's of the HAs gathered at three different intensity and nine distict frequencies were compared.The amount of deviations from the target gains and percentage rates of attaining targets of hearing aids were determined. Results: Means of REIG scores of hearing aids obtained at their initial fittings were found to be lower than NAL-NL2 target gains. There was a siginificant difference between the hearing aids when they were compared with each other at their initial fittings (p<0.05). Conclusion: The study showed that REIG scores of two different brands of hearing aids obtained at their initial fittings could not attain their target gains. Therefore it was concluded that, in order to attain the target gains in hearing aid fittings, real ear measurement (REM) should be utilised. Key Words: Real ear measurement, hearing aid, real ear insertion gain