Investigation of a Novel Completely-in-the-Canal Direct-Drive Hearing Device

Abstract

Hypothesis Whether a prototype direct-drive hearing device (DHD) is effective in driving the tympanic membrane (TM) in a temporal bone specimen to enable it to potentially treat moderate to severe hearing loss. Background Patient satisfaction with air conduction hearing aids has been low due to sound distortion, occlusion effect, and feedback issues. Implantable hearing aids provide a higher quality sound, but require surgery for placement. The DHD was designed to combine the ability of driving the ossicular chain with placement in the external auditory canal. Methods DHD is a 3.5 mm wide device that could fit entirely into the bony ear canal and directly drive the TM rather than use a speaker. A cadaveric temporal bone was prepared. The device developed in our laboratory was coupled to the external surface of the TM and against the malleus. Frequency sweeps between 300 Hz to 12 kHz were performed in two different coupling methods at 104 and 120 dB, and the DHD was driven with various levels of current. Displacements of the posterior crus of the stapes were measured using a Laser Doppler Vibrometer. Results The DHD showed a linear frequency response from 300Hz to 12kHz. Placement against the malleus showed higher amplitudes and lower power requirements than when the device was placed on the TM. Conclusions DHD is a small completely-in-the-canal device that mechanically drives the TM. This novel device has a frequency output wider than most air conduction devices. Findings of the current study demonstrated that the DHD had the potential of being incorporated into a hearing aid in the future.

Completely‐in‐the‐Canal Magnet‐Drive Hearing Device

“…This design would lead to smaller size, lower power consumption (about 20 mA for 70-dB gain), and minimal mass loading effect. 2 At the current stage, the device prototype does not include battery or digital signal processing. Adding these parts, in the future, will probably double the length of the device.…”

“…Technical details of the device are published elsewhere. 2 Frequency response and noise generation of the MHD were validated prior to cadaver testing. This study was exempt from review by the Institutional Review Board at the University of California, Irvine.…”

Development of a novel completely-in-the-canal direct-drive hearing device

“…In an attempt to address the drawbacks of commercially available HAs, a hearing device was conceptualized that combines the advantages of various types of HAs into a single device. Previous work has shown the feasibility of using a device to drive the tympanic membrane (TM) for production of sound . The authors have been designing and developing the direct‐drive hearing device (DHD) prototype, a novel device that fits entirely into the bony external auditory canal (EAC), touches the TM, and directly drives the TM.…”