In-vivo characterisation of an implanted microphone and totally implantable active middle ear implant.

OBJECTIVE: To objectively evaluate acoustic sensitivity of the implanted microphone, and maximum stable gain of a totally implantable active middle ear implant. DESIGN: Prospective, single centre evaluation. STUDY SAMPLE: Fourteen adult patients. RESULTS: Microphone sensitivity is approx. 10 dB lower than an externally worn conventional hearing aid, at frequencies up to 4000 Hz, and substantially lower at higher frequencies. The masking level due to microphone noise, which determines the softest test tones that can be detected, is estimated at <20 to <30 dB HL up to 1000 Hz, and <40 dB HL at higher frequencies. Maximum stable effective gain is the maximum amplification achievable without causing feedback whistling. In sensorineural hearing loss (SNHL) cases, it is 30-40 dB at frequencies up to 2000 Hz, allowing to compensate for even the maximum recommended hearing loss (60-70 dB HL). In both SNHL and mixed hearing loss (MHL) cases, maximum stable effective gain is lower (+20 to -30 dB) around 3000-6000 Hz. CONCLUSIONS: Microphone sensitivity is high enough to achieve aided thresholds of 20-40 dB HL. A strong correlation between actuator coupling efficiency and maximum stable effective gain implies that any effort to improve actuator efficiency should also increase the available gain.

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.

The first results of a totally implanted active middle ear device.

PURPOSE: The aim of this study was to assess the first outcomes of a fully implantable active middle ear device. METHODS: Retrospective observational nonrandomized group study. SETTINGS: Private hospital. Fifteen patients underwent device implantation between December 2014 and June 2017. The pre-operative and post-operative air conduction (AC) and bone conduction (BC) thresholds were evaluated. The functional gain, speech perception in silence and in noise, and localization abilities were also analyzed. RESULTS: Sixteen active middle ear implantations were performed. Post-operatively, the mean pure tone thresholds were 50.5 dB ( ± 12.64) for BC and 64.9 dB ( ± 15.36) for AC. No differences were found between the post-operative and pre-operative audiometric thresholds before activating the system (p > 0.05). Post-operatively, the mean thresholds in the free field after the device was activated were 46.8 dB, 45.75 dB, 42.6 dB, and 43.38 dB at 1, 3, 6, and 12 months, respectively. The global results of speech understanding in silence were 50.7 dB, 47.18 dB, 42 dB, and 42 dB for 1, 3, 6, and 12 months, respectively. Patients with mixed hearing loss had better results than those with sensorineural hearing loss. Speech discrimination in noise and localization was improved. CONCLUSIONS: Despite the small number of patients, our results confirmed that this fully implantable active middle ear device is a viable treatment for patients with moderate-to-severe sensorineural hearing loss who cannot or do not want to use traditional hearing aids for clinical or cosmetic reasons.