Air- and Bone-Conducted Sources of Feedback With an Active Middle Ear Implant

Active Middle Ear Implant Patient Outcomes With Adaptive Feedback Canceller

OBJECTIVE

Evaluation of the audiological patient performance with an upgrade of the firmware from the fixed feedback canceller (FFC) to the adaptive feedback canceller (AFC) on an active middle ear implant.

STUDY DESIGN

Retrospective observational nonrandomized group study.

SETTING

Private hospital.

PATIENTS/INTERVENTIONS

From March 2018 to September 2019, 15 patients implanted with an active middle ear implant, with 6 or more months of experience with a FFC system, were upgraded to an AFC algorithm.

MAIN OUTCOME MEASURES

Functional gain, speech perception in silence and in noise, and sound localization capacities were examined. Feedback reduction was also analyzed.

RESULTS

Thirteen patients were analyzed. Pure tone audiometric evaluation with FFC (mean value of 48.02 dB) compared with AFC at 1 (mean value of 49.12 dB) and 6 months (mean value of 42.75 dB) revealed no statistically significant differences (p = 0.889 and p = 0.358 respectively).In speech discrimination in silence, clinically relevant improvements were observed with AFC at 1 and 6 months, with a mean value of 41.5 and 38.3 dB, respectively (p = 0.03 and p = 0.021 correspondingly). In speech discrimination in noisy environments, we observed an improvement of the different conditions tested. No differences were found in localization capacities between FFC and AFC at the two different moments of evaluation.

CONCLUSIONS

AFC is more effective than FFC in cancelling feedback and improving sound quality, allowing for better speech understanding in silence and in noise.

In-situ sensitivity of a totally-implantable microphone

One of the key components of fully-implantable hearing devices is the implantable microphone. A crucial parameter when characterizing implantable microphones is the acoustic sensitivity, as it is one of the input parameters for the fitting algorithm and influences the achievable gain. The aim of our study was to investigate the sensitivity of an implanted subcutaneous microphone over time to answer two research questions: (1) How does the sensitivity change once the microphone is implanted under the skin (pre-op versus in-situ)? and (2) How does the sensitivity change from short-term to mid-term? We have measured the in-situ microphone sensitivity in three subjects implanted with a fully-implantable active middle ear implant from 2 weeks up to 20 weeks after implantation with a research software. The microphone sensitivity changed after implantation with clinically relevant changes around the resonance frequency of the microphone. Based on our results, it is essential to measure the in-situ microphone sensitivity at the time of initial fitting of the implant. Once implanted no clinically relevant changes in the microphone sensitivity were observed over time, with a clear decrease in variability over time.