Age Effects on Cochlear Reflectance in Adults

Abstract

Objectives: Cochlear reflectance (CR) is the cochlear contribution to ear-canal reflectance. CR is a type of otoacoustic emission that is calculated as a transfer function between forward pressure and reflected pressure. The purpose of this study was to assess effects of age on CR in adults and interactions among age, sex, and hearing loss. Design: Data were collected from 60 adults selected for their age (e.g., 20–29, 30–39, 40–49, 50–59, 60–69, 70–79 years) and normal middle ear status. A wideband noise stimulus presented at three stimulus levels (30, 40, 50 dB SPL) was used to elicit CR. Half-octave bands of CR signal magnitude (CRM), CR noise, and the CR signal-to-noise ratio (CR-SNR) were extracted from the wideband CR response. Regression analyses were conducted to assess interactions among CR, age, sex, and pure-tone thresholds at closely matched frequency bands across stimulus levels. Results: Although increased age was generally associated with lower CRM and CR-SNR at some band frequencies and stimulus levels, no significant effects of age remained after controlling for effects of pure-tone thresholds. Increases in pure-tone thresholds were associated with lower CRM and CR-SNR at most frequency bands and stimulus levels. Effects of hearing sensitivity were significant at some frequencies and levels after controlling for age and sex. Conclusions: When effects of age were controlled, adults with better hearing had significantly larger CRM and CR-SNR than those with poorer hearing. In contrast, when effects of hearing were controlled, no significant effects of age on CRM and CR-SNR remained.

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

“…Previously, we observed that older adults showed significantly different across-frequency patterns of TEOAEs depending on whether their audiograms were classified into an older-normal, metabolic, sensory, or metabolic + sensory category (Vaden et al, 2018). In the current study, we predicted that higher metabolic estimates are associated with broad declines in the DPOAE response across stimulus frequency (Kamerer, Kopun, Fultz, Allen, et al, 2019; Kamerer, Kopun, Fultz, Neely, & Rasetshwane, 2019; Neely et al, 2019) as with CR responses (Fultz et al, 2020; Neely et al, 2019; Rasetshwane et al, 2015). Similarly, we predicted that higher sensory components are associated with steeper slopes for DPOAE and CR responses with weaker responses at the highest frequencies (Vaden et al, 2018).…”

“…However, there were no significant associations between sensory estimates and CR response configuration at any presentation level. This was unexpected, given that CR response magnitudes were significantly associated with hearing sensitivity in the original studies (Fultz et al, 2020;Neely et al, 2019;Rasetshwane et al, 2015). The absence of a sensory effect despite significant metabolic effects on CR response configuration suggests that there may not have been a sufficient range of sensory estimates for sensitivity to their effects (Figure 4(C)).…”

“…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.…”

“…The relatively small MUSC sample ( N = 15; Figure 5) was combined with the dataset from BTNRH ( N = 119) for a single analysis. Both measures were collected from the BTNRH participants for the same experiment (Neely et al, 2019), while the MUSC participants had each measure collected separately for the CR study (Fultz et al, 2020) and a longitudinal age-related hearing loss study. To limit possible longitudinal changes in the MUSC sample, the participants selected for analysis had less than 4 years between visits (average = 1.2 years) and average pure-tone threshold changes less than 7.5 dB HL (average = 4.7 dB HL).…”

“…Most of the MUSC participants were part of a longitudinal cohort study of age-related hearing loss between 1987 and the present, they were recruited from the community and had good general health with no evidence of conductive hearing loss or active otologic/neurologic disease. The MUSC data includes a subset of individuals whose audiograms, DPOAEs, CRs, noise histories, and demographic information were previously reported (Fultz et al, 2020; Vaden et al, 2022). The participants in the original studies at BTNRH (Kamerer, Kopun, Fultz, Allen, et al, 2019; Kamerer, Kopun, Fultz, Neely, & Rasetshwane, 2019; Neely et al, 2019; Rasetshwane et al, 2015) were recruited from a database of potential participants who volunteered for hearing research through various outpatient clinics and community-based recruitment events.…”