Performance evaluation of a novel piezoelectric subcutaneous bone conduction device

Abstract

Objectives Evaluation of the transfer function efficiency of a newly-developed piezo-electric actuator for active subcutaneous bone conduction hearing aid. Methods The experiments were conducted on four Thiel embalmed whole head cadaver specimens. A novel actuator based on piezo-electric transduction (PZTA), part of a subcutaneous bone conduction hearing aid device, was sequentially implanted on three locations: 1) Immediately posterior to pinna; 2) 50-60 mm posterior to pinna, approximately the same distance as between the BAHA (bone anchored hearing aid) location and the ear canal, but the same horizontal level as location 1; 3) the traditional BAHA location. Using a single point 3-dimensional laser Doppler vibrometer (LDV) system, three types of motion measurements were performed at the cochlear promontory for each stimulation location: 1) ipsilateral side, 2) contralateral side, 3) measurements 1 and 2 were repeated after mastoidectomy on the ipsilateral side. Results On average, stimulation at locations 1 and 2 show a trend for higher promontory motion relative to location 3 (BAHA location) above 1 kHz. Stimulation at location 1 had an average improvement of 1-6 dB at 2-4 kHz, and 1-18 dB at 6-8 kHz. The spatial composition of the motion showed significant contributions from both in-plane and out-of-plane (along ear canal) motion components, with in-plane components being dominant at mid and high frequencies for locations 2 and 3. Stimulation at locations 1 and 3 produced similar transcranial attenuation at mid frequencies (0.6-4 kHz), with a potential trend of higher attenuation (seen in 3 or the 4 samples) for location 1 at higher frequencies (>4 kHz). The mastoidectomy affected negatively mostly the high frequencies (6-8 kHz) for stimulation at location 1, with no significant change for location 3. Conclusion The sound transfer function efficacy of a novel subcutaneous bone conduction device has been quantified, and the influence of stimulation location and mastoidectomy have been analyzed based on promontory motion in Thiel-preserved cadaver heads.

Experimental investigation of promontory motion and intracranial pressure following bone conduction: Stimulation site and coupling type dependence

“…All coupling types showed a significant transcranial gain (i.e., negative attenuation) of approximately 2-5 dB, based on the combined motion. Such a transcranial gain has also been observed in previous research with 1D and 3D velocity measurement in cadaver heads (Stenfelt and Goode, 2005b;Dobrev and Sim, 2018;Dobrev et al, 2018b) and in 1D velocity measurements in patients (Stenfelt, 2012;Eeg-Olofsson et al, 2011a, 2011b. A hypothesis for its occurrence is based on a rigidbody-like motion of the head at low frequencies, composed of a translation (approximately along the stimulation direction) and rotation (particularly around the superior-inferior axis) components.…”

“…6 A-C might be due to a combination of stronger transcranial attenuation at the mastoid location and the more efficient coupling provided by the BI300. It could then be hypothesized that direct bone coupling (BI300 or implanting of the actuator) located closer to the cochlea, such as in the case of some newly developed BCHA actuators (Håkansson et al, 2010;Dobrev et al, 2018b), would provide better selectivity for stimulation of the ipsilateral relative to the contralateral cochlea.…”

Transcutaneous and percutaneous bone conduction sound propagation in single-sided deaf patients and cadaveric heads

“…Two major parameters affecting BC transmission are the geometric proximity of the source to the cochleae and skin dampening. Ipsilateral promontory motion (PM) increases with proximity of the stimulation to the ipsilateral cochlea in cadaver heads (Dobrev et al 2018;Eeg-Olofsson et al 2008), while having little effect on the contralateral side (Rigato et al 2019;Stenfelt and Goode 2005). The same was found in living patients based on measurement of hearing thresholds (Reinfeldt et al 2014).…”

Experimentelle Evaluation des Adhear, eines neuen transkutanen Knochenleitungshörgeräts

“…1). Der Aufbau und die Messungen erfolgten wie zuvor ausführlich beschrieben [12][13][14]. Es wurde die 3-dimensionale (3D) Vibration des ipsilateralen und kontralateralen Promontoriums mit dem Single-point-3D-Laser-Doppler-Vibrometer (LDV) (3D CLV 3000, Polytec GmbH, Deutschland) gemessen, der an einem Roboterarm (KR 16, KUKA, Deutschland) fixiert war.…”

“…Die Daten wurden mittels eines eigens entwickelten Matlab-Skripts (Matlab 2018a, MathWorks, USA) analysiert. Für jeden einzelnen Messpunkt wurden über 2 mathematische Schritte die eine Bewegungsachse rechtwinklig und die 2 weiteren Bewegungsachsen tangential zur Schädeloberfläche ausgerichtet [12]. Schließlich wurden die Daten 3 Qualitätsüberprüfungen unterworfen.…”