Reliability and Clinical Test Performance of Cochlear Reflectance

Abstract

Objective Cochlear reflectance (CR) is the cochlear contribution to ear-canal reflectance. CR is equivalent to an otoacoustic emission (OAE) deconvolved by forward pressure in the ear-canal. Similar to other OAE measures, CR level is related to cochlear status. When measured using wideband noise stimuli, potential advantages of CR over other types of otoacoustic emissions include (1) the capability to cover a wider frequency range more efficiently by requiring fewer measurements, (2) minimal influence on the recorded emission from the measurement system and middle ear, (3) lack of entrainment of spontaneous OAEs, and (4) easier interpretation due to the existence of an equivalent linear model, which validates the application of linear systems theory. The purposes of this study were to evaluate the reliability, assess the accuracy in a clinical screening paradigm, and determine the relation of CR to audiometric thresholds. Thus, this study represents an initial assessment of the clinical utility of CR. Design Data were collected from 32 normal-hearing (NH) and 58 hearing-impaired (HI) participants. A wideband noise stimulus presented at seven stimulus levels (10 to 70 dB SPL, 10-dB steps) was used to elicit the CR. Reliability of CR was assessed using Cronbach’s α, standard error of measurement, and absolute differences between CR data from three separate test sessions. Test performance was evaluated using clinical decision theory. The ability of CR to predict audiometric thresholds was evaluated using regression analysis. Results CR repeatability across test sessions was similar to that of other clinical measurements. However, both the accuracy with which CR distinguished NH from HI ears and the accuracy with which CR predicted audiometric thresholds were less than reported in previous studies using distortion-product OAE measurements. Conclusion CR measurements are repeatable between test sessions, can be used to predict auditory status and are related to audiometric thresholds. However, under current conditions, CR does not perform as well as other OAE measurements. Further developments in CR measurement and analysis methods may improve performance. CR has theoretical advantages for cochlear modeling, which may lead to improved interpretation of cochlear status.

Cochlear Reflectance and Otoacoustic Emission Predictions of Hearing Loss

“…This study extends our previous work on the relationship between CR and auditory status (Rasetshwane et al 2015). The main goals of this study were to (1) to compare the accuracy of CR and DPOAEs in terms of identification of auditory status (i.e., normal versus impaired), which we refer to as test performance and (2) to compare the accuracy of CR and DPOAEs in their prediction of audiometric thresholds.…”

“…The inclusion criteria for tympanometry (Otoflex 100, Madsen) required a peak-compensated static acoustic admittance between 0.3 and 2.5 mmhos and peak tympanometric pressure between −100 and +50 daPa. The upper limit of the admittance range is higher than typically used but was selected for consistency with previous studies in our laboratory (e.g., Rasetshwane et al 2015;Sieck et al 2016). The inclusion criterion for bone conduction (B71, Radioear) required air-bone gaps ≤ 10 dB.…”

“…CR data-collection time was, on average, 35 minutes per session. CR measurements were made following procedures described by Rasetshwane et al (2015). Thévenin-equivalent source parameters for the ER-10X were determined prior to data collection.…”

“…Alternatively, CR may be defined by a transfer function between the forwardpropagating component of pressure measured in the ear canal and the component of the reflected pressure that comes from the cochlea. The CR properties that allow its separation from contributions that come from the middle ear, ear canal, and measurement system are its longer latency and dependence on stimulus level (Rasetshwane and Neely 2012;Rasetshwane et al 2015). Our procedure for measuring CR is described in the Methods section.…”

Metabolic and Sensory Components of Age-Related Hearing Loss: Associations With Distortion- and Reflection-Based Otoacoustic Emissions

“…The CR response datasets were combined into a single analysis rather than testing for replications, because of the relatively small sample size of the MUSC dataset (Figure 4) and identical protocols across sites. The same equipment and procedures were used because the Fultz et al (2020) experiment was implemented in collaboration with the coauthors at BTNRH (detailed in Fultz et al, 2020; Neely et al, 2019; Rasetshwane et al, 2015). The stimuli consisted of a wideband linear swept-frequency chirp at 60 dB SPL and WBN presented at 30, 40, and 50 dB SPL.…”