Maximum usable real-ear insertion gain with ten earmold designs.

The present study compared the maximum usable real-ear insertion gain (REIG) permitted by 10 earmold designs that varied in the amount of occlusion. These earmolds were coupled to a high-gain hearing aid (Phonak Super-Front PPCL). In addition, the specificity of a nonoccluding earmold for the Oticon E43 hearing aid was examined. Maximum usable REIG, defined as the insertion gain obtained with the hearing aid set to just below the point of acoustic feedback after jaw movement, was determined in 10 hearing-impaired subjects. The results showed that earmold style had a significant effect on the magnitude of maximum REIG. Among the occluding earmolds, no difference in REIG was noted among the shell, canal, and skeleton earmolds, while the standard earmold permitted the least amount of maximum REIG. For the nonoccluding earmolds, those that were more occluding permitted greater REIG than those that were less occluding. The amount of occlusion on a nonoccluding earmold affected the maximum REIG provided by the Oticon E43 hearing aid.