Evaluation of a New Coupler for the Floating Mass Transducer

Abstract

Objective: Optimal placement is an important factor in the acoustic performance of the Vibrant Soundbridge Floating Mass Transducer (FMT) in the round window niche (RW). The purpose of this study was to evaluate the acoustic performance of a new modified FMT designed to optimally contact the RW.

Method: Testing of the modified FMT without fascia and with fascia between the RW membrane and the device was performed in six human temporal bones. A small hole was made on the promontory to expose the endosteum. Cochlear fluid displacement was measured through the hole using a laser Doppler vibrometer.

Results: The mean cochlear fluid response of the FMT placed on the RW without fascia was equivalent to a 76.3 to 111.6 dB SPL input at the tympanic membrane at 0.5 to 8.0 kHz. The mean cochlear fluid response of the FMT placed on the RW with fascia produced a response of 87.5 to 119.1 dB SPL at the same frequencies. There was a tendency for the FMT placed on the RW with fascia to provide better transmission at several frequencies between 0.5 and 8.0 kHz than without fascia. However, this did not reach statistical significance.

Conclusion: In this temporal bone model, the modified FMT placed on the RW provide similar and reasonable performance both with and without fascia in the RW niche. It appears superior to a conventional FMT used in the RW and is easier to insert.