The purpose of this study was to develop a strategy for verifying the gain/frequency characteristics of nonlinear hearing aids used by infants, by converting their thresholds to 2cm
3 coupler SPL. Twenty-three infants (age: 13 to 30 months) with hearing impairment (45 ears) were tested by visual reinforcement audiometry using ER-3A insert earphones coupled with custom earmolds to measure the MRTs (minimum response thresholds) across frequencies in dBHL. To convert dBHL to 2cm
3 coupler SPL, the CDD (coupler-to-dial difference) values were added to the MRTs, which could display the MRTs on the 2cm
3 SPL-gram developed by Ohwada. The strategy was based on the theory that the RECD (real-ear-to-coupler difference) values of wearing a hearing aid would be equal to those of inserting the ER-3A, because of the coupling with the same custom earmold. For verification of the hearing aid characteristics, the converted MRTs were compared to the output levels of nonlinear hearing aids measured in a 2cm
3 HA-2 coupler with input levels of 50dB, 65dB and 80dBSPL. Strong correlations (r>.86) were found among them in the 500Hz, 1000Hz and 2000Hz range. In conclusion, comparison of the converted MRTs with the output levels of hearing aids on a 2cm
3 SPL-gram was useful for verifying the suprathresholds characteristics of nonlinear hearing aids for infants.
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