Adapting Hearing Devices to the Individual Ear Acoustics: Database and Target Response Correction Functions for Various Device Styles.
Florian Denk, Stephan M A Ernst, Stephan D Ewert and 1 others
PMID 29877161WHAT IT FOUND
Individualized diffuse-field correction gives the smallest modeled sound error for hearing devices, especially in ear-canal styles.
Behind-the-ear microphones still cannot reproduce open-ear sound.
Key findings
01Individual diffuse-field correction produced the lowest modeled residual distortion for all microphone locations.
02Free-field correction remained close to diffuse-field correction only at the blocked ear canal entrance and worsened at more distant microphone locations.
03The benefit of individual correction decreased with distance from the eardrum and was smallest at behind-the-ear locations.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The spectral distortion result is a model estimate, not a listening test, and the authors state final judgments need subjective listening experiments. The study measured transfer functions and modeled distortion, not speech recognition, comfort, or patient outcomes. The sample was 16 human subjects and 2 dummy heads, and the outcome was modeled distortion, not clinical listening performance. Dummy-head correction functions were 2 to 5 dB lower around the main resonance than human averages. A low-frequency ripple in free-field data was probably caused by reflections from seated subjects, which may affect free-field corrections. Individual correction gave the least benefit for behind-the-ear devices, so the findings may not translate to transparent sound for those styles.
Declared interests
The paper names the Deutsche Forschungsgemeinschaft as funder.
The easy way to misread this
Do not conclude that individualized hearing-device correction improves listening outcomes. The paper reports modeled spectral distortion in 16 subjects and dummy heads, and the authors state final judgments need subjective listening experiments.