Real ear measurement (REM) and auditory performances with open, tulip and double closed dome in patients using hearing aids.

The aim of the study is to evaluate the importance of acoustic modifications generated by different commercially available ear-tips, focused on domes of receiver in the canal hearing aids using Real Ear Measurement (REM). We enrolled 110 people selecting 200 ears bearers of hearing aids. In every patient, we performed REM and audiological tests with three different dome types: Open, Tulip and Double Closed (DC). Data about real-ear occluded gain (REOG), Pure Tone Average (PTA), Word Recognition Score (WRS) with aids switched on in Free Field, Ear and Auditory Comfort were collected and analyzed. REOG gain was statistically significant different between the three types of dome, with a DC that always closes the external auditory canal (EAC) (p < 0.001). There was no statistically significant difference between the PTA (p = 0.11). Regarding the WRS there were statistically significant differences between Open and DC dome (p < 0.001) and between Tulip and DC dome (p < 0.001), with worse discrimination when using DC. Both auditory and ear comfort are worse in the DC than in the other two domes (p < 0.001). From measured REOG gain values, in 135 cases Tulip dome does not occlude the EAC, with a statistically significant difference compared to DC (p < 0.001; Odd Ratio 0.0012; 95% CI 0.001-0.0196). Our study confirms the necessity to perform REM to evaluate if the prescription target is achieved, especially when tulip domes are used, because they may not occlude the ear canal, causing in some cases the reduction of the vocal discrimination.