Methods and reference data for middle ear transfer functions

Abstract

Human temporal bone specimens are used in experiments measuring the sound transfer of the middle ear, which is the standard method used in the development of active and passive middle ear implants. Statistical analyses of these experiments usually require that the TB samples are representative of the population of non-pathological middle ears. Specifically, this means that the specimens must be mechanically well-characterized. We present an in-depth statistical analysis of 478 data sets of middle ear transfer functions (METFs) from different laboratories. The data sets are preprocessed and various contributions to the variance of the data are evaluated. We then derive a statistical range as a reference against which individual METF measurements may be validated. The range is calculated as the two-sided 95% tolerance interval at audiological frequencies. In addition, the mean and 95% confidence interval of the mean are given as references for assessing the validity of a sample group. Finally, we provide a suggested procedure for measuring METFs using the methods described herein.

Objective preclinical measures for bone conduction implants

“…It is therefore the most efficient stimulation position according to this measure, which aligns with the findings of Fierens et al (2022) . This consistent observation provides further evidence for the precision of this measurement technique ( Rosowski et al, 2007 ; Koch et al, 2022 ). However, it is essential to note that the velocity is measured in only one dimension as opposed to experiments performed by Dobrev et al (2016 , 2017) .…”

“…Most of the measurements obtained from the middle ear transfer functions fall within the ranges reported by Koch et al (2022) , indicating that the specimens used in this study are representative of the population. Notably, apart from one specimen at a specific frequency, no significant differences were found between the measurements obtained before and after sensor insertion.…”

“…The middle ear transfer functions of one specimen (1L) before and after the insertion of pressure sensors in the cochlea are shown in Figure 2A , while the transfer function of all specimens can be found in Supplementary Figure S1 . For 97% of the measurements, the 95% confidence interval overlaps with the range published by Koch et al (2022) , indicating that the specimens are representative of the population. For only one single frequency in one specimen (4L at 1526 Hz), a significant difference was found between the measurements before and after sensor insertion.…”

“…The middle ear transfer function (METF), i.e., the ratio of the stapes velocity to the ear canal pressure, is measured before and after sensor insertion. Comparing the measured transfer function with the range of Koch et al (2022) enables us to check whether the specimen is representative of the population. However, this range is not an exclusion criterion.…”

Transverse flow under oscillating stimulation in helical square ducts with cochlea-like geometrical curvature and torsion

“…Based on reported data [27][28][29], we chose three mean inlet velocity amplitudes To shorten the duration of the initial transient state, the amplitude of the inlet pressure P 0 was ramped up smoothly over the first few cycles. To ensure that the initial transient is washed out, we retrieved results after a sufficient number of cycles, e.g., after 21 cycles at 256 Hz.…”