Testing a Method for Quantifying the Output of Implantable Middle Ear Hearing Devices

Abstract

This report describes tests of a standard practice for quantifying the performance of implantable middle ear hearing devices (also known as implantable hearing aids). The standard and these tests were initiated by the Food and Drug Administration of the United States Government. The tests involved measurements on two hearing devices, one commercially available and the other home built, that were implanted into ears removed from human cadavers. The tests were conducted to investigate the utility of the practice and its outcome measures: the equivalent ear canal sound pressure transfer function that relates electrically driven middle ear velocities to the equivalent sound pressure needed to produce those velocities, and the maximum effective ear canal sound pressure. The practice calls for measurements in cadaveric ears in order to account for the varied anatomy and function of different human middle ears.

A MEMS Condenser Microphone-Based Intracochlear Acoustic Receiver

“…They were somewhat below the mean of the reference data at frequencies above 700 Hz. This is in agreement with data for the ME transfer function of the investigated temporal bone, which also indicated a lower than average ASTM standard response [3], [43] at higher frequencies and consequently lower cochlear input. The corresponding phase of the transfer function is shown in Fig.…”

“…Preparation of the human temporal bone for ICSP measurements followed a standard surgical approach [41], [42]. Prior to drilling access to the inner ear, a standard conformity test of the ME was performed by quantifying the TBME-01353-2016 6 ME transfer function and comparing it to the ASTM practice ME standards [3], [43]. The cochlear access (cochleostomy) to the scala tympani (ST, cf.…”

Sound pressure distribution within natural and artificial human ear canals: Forward stimulation

“…It is unlikely that post-mortem changes in the EC or middle-ear acoustical properties affected our results, as the EC walls are effectively rigid in both live and cadaver adult ears, and comparisons of middle-ear acoustic (Rosowski et al, 1990) and mechanical properties in live subjects or patients (e.g., Goode et al, 1993;Chien et al, 2006Chien et al, , 2009Rosowski et al, 2007) have shown no appreciable post-mortem differences.…”

Round Window Membrane Implantation with an Active Middle Ear Implant: A Study of the Effects on the Performance of Round Window Exposure and Transducer Tip Diameter in Human Cadaveric Temporal Bones

“…The mechanical properties of the middle and inner ear were first confirmed by measuring the stapes and RW membrane velocities with acoustic stimulation from the external auditory canal via an appropriately calibrated insert earphone. The bones with acoustic stapes-velocity transfer functions outside the range described in the criteria by Rosowski et al [2007] were excluded. In all cases, the bony overhang of the RW niche was initially preserved.…”

“…Our bone preparation allowed us to achieve LDV laser angles for stapes velocity measurements between 65° and 80° from the axis of piston-like stapes motion. The stapes and RW velocities were first measured with acoustic closed-field stimulation before driving the RW with an AMEI in order to confirm if the stapes and the RW velocities were in the normal range defined by Rosowski et al [2007]. Stapes velocity was again measured by stimulating the RW with the AMEI.…”