An Empirical Study On Acoustic Feedback Path Across Hearing Aid Users

Acoustic feedback is one of the major problems in hearing aid applications. During a fitting session of a modern hearing aid, typically a feedback path prediction or an in situ measurement of feedback path is used as part of the gain and earpiece prescription to minimize the risk of feedback problems. It is well known that there are a lot of variations in feedback paths across users due to ear differences, however, there is limited knowledge from published studies to actually quantify these variations, especially for the earpiece types as domes and micro molds which became popular since the introduction of receiver-in-the-ear (RITE) style hearing aids. In this empirical study, we measured feedback paths on different users wearing a RITE style hearing aid fitted with different domes and micro molds. Our results confirmed that there are large variations across users/ears, and magnitude differences in measured feedback paths can be more than 60 dB for otherwise identical hearing aid and earpiece type.