Prof. Dr. Steffen Kreikemeier, Aalen
Video 4 2017
“Prescription procedures vs individual dynamic-oriented percentile fitting – how much audibility is reasonable?”
NAL-NL2 takes effective audibility into account, which can result in a real-ear aided response (REAR) below the threshold of hearing. As a result, not all parts of speech are audible (Keidser et al., 2011).
The aim of the presented study was to compare an evidence-based procedure (NAL-NL2) with dynamic-oriented percentile fitting. The hearing aids were programmed to amplify speech at an input level of 65 dB SPL so as to make as many parts of speech audible as possible. Subjects with and without hearing aid experience participated in this study. Both NAL-NL2 and the dynamic-orientated percentile fitting were verified in situ and the 50 percent speech recognition threshold (SRT) was determined.
The results show that the target gain for dynamic-oriented fitting (audibility of all parts of speech) is difficult, or even impossible, to obtain using standard RIC hearing aids and domes. When target levels were achieved, the fitting was rated as too loud even by experienced hearing aid users. These results confirm initial experience gained with loudness-based percentile fitting – LPFit (Kreikemeier, 2011).