Reproducibility and Tester Variability of Real Ear Insertion Gain

Reproducibility and Tester Variability of Real Ear Insertion Gain Jon Øygarden, Lars Gunnar Rosvoldaunet, Thomas Dalmo, Tom Lyngaas Holsæter and Camilla Wilson Audiology, Department of Health Science, NTNU – Norwegian University of Science and Technology The European standard EN 15927 ‘Services offered by hearing aid professionals’ clause 5.5.4 proposes three main methods for verification of improvement in hearing ability (A. speech audiometry in sound field, B. surveys with real-ear measurements and C. questionnaire concerning the perceived benefit from the hearing aid system). The standard states that at least one of these methods should be used and the results reviewed with the client. In this study we evaluated reproducibility of method B by measuring real ear insertion gain (REIG) for a group of 12 hearing aid users. Several types of hearing instruments were included: behind-the-ear (BTE), receiver-in-the-ear (RITE), receiver-in-the-aid (RITA) and one completely-in-canal (CIC). The hearing aid users were volunteers from ‘professional patients’ group and had received the aids prior to this study. For 19 of the ears fitted with hearing aids, insertion gain was measured repeatedly by two audiology students (audiologist 1 and 2). Both audiologists performed independent measurement sessions on each of the hearing aids. The reproducibility data for REIG will be presented for frequency bands 250, 500, 750, 1500, 2000, 3000, 4000, 6000 and 8000 Hz. Measures of instant reproducibility (measurements conducted without removing the tube from the ear canal), short term reproducibility (new complete measurement session performed at the same visit) and long term reproducibility (new complete measurement session at a follow up visit 1-7 days after the initial measurement). Data from real ear measurements performed by audiologist 1 and 2 were compared. Results indicated that 90 % of the REIG measurements for all the frequency bands showed a deviation less than ± 3 dB from the average REIG response of the hearing aid, and 54 % had a deviation less than ± 1 dB.