High-Frequency Distortion-Product Otoacoustic Emission Repeatability in a Patient Population

Abstract

HF DPOAEs were repeatable across four test trials for all three paradigms measured in a group of CF patients. These results are encouraging for the measurement of HF DPOAEs to be monitored in those exposed to ototoxic agents.

Acquisition and Repeatability of High-Frequency Distortion Product Otoacoustic Emissions Using Two Different Calibration Methods in Newborns

“…In adults and children at the highest frequencies tested (up to 16 kHz), average noise floors are less and DPOAE levels are higher than were recorded in the current study [5,[48][49][50]52]. The testing environment for the current study also could have contributed to overall higher noise floors than previously recorded in clinical and patient rooms where it was only the tester and the patient [51,53]. Often, family members in addition to the parents were present during testing, as were nursing staff.…”

“…If only frequencies between 10 through 16 kHz are examined for newborns, the average absolute difference between trials was 2.82 (SD = 2.68) for FPL and 3.43 (SD = 2.62) for SPL calibrations. These results are less variable than for young, normal-hearing adults using SPL calibration [5] and more variable than cystic fibrosis patients monitored between ototoxic treatments using alternate calibration techniques [51] with average absolute differences between trials of 5.15 (SD = 4.40) and 1.96 (SD = 2.19), respectively. It should be noted that the newborns in this study only had DPOAEs measured in one session compared to the other literature referenced for comparison which involved data collection minimally across several hours, but more often at least two different days.…”

“…The short-dashed lines denote the average noise floor across the two test trials for those who had present DPOAEs. It should be noted that, despite using research equipment, the average noise floor levels are higher (worse) at all frequencies than have been recorded when testing in a quiet room within a clinic [51] and in a room housed in an infusion center [53], but are no worse, and actually better, than the typical noise floor measured with clinical equipment. For DPOAE levels to be considered present a signal-to-noise ratio (SNR) of 6 dB and a level greater than −20 dB SPL needed to be met, so not every data point includes data deemed present from all 26 ears at each of the seven frequencies tested.…”

“…Ideally, cochlear health would be monitored at the highest frequencies producing a response as this is where damage initially occurs due to ototoxic drug exposures [47]. Using customized equipment, HF (up to 16 kHz) DPOAEs have been measured [5,48] and are repeatable across testing sessions in normal-hearing young adults and children [5,[49][50][51][52], in those with cystic fibrosis tested between ototoxic treatments [51], and identified the earliest signs of damage at the highest frequencies with present DPOAEs in adults exposed to ototoxic agents [53], but have not been recorded in newborns. While DPOAEs may not be recorded at the highest frequencies of human hearing for each individual based on their cochlear health, it is imperative to monitor the highest frequencies with a response in individuals exposed to ototoxic agents to identify the earliest signs of damage [53,54].…”

Emerging Distortion Product Otoacoustic Emission Techniques to Identify Preclinical Warning Signs of Basal Cochlear Dysfunction Due to Ototoxicity

“…It has also been demonstrated that higher frequency (>8 kHz) information is most valuable for timely detection of cochlear dysfunction and specifically utilizing high-frequency DPOAEs [16,27]. Furthermore, the feasibility of measuring DPOAEs beyond 8 kHz has been demonstrated across a range of ages (10 to 65 years) with normal-hearing [21] as well as repeatable over time in healthy, young, normal-hearing adults and in a patient population not exposed to ototoxic medications during monitoring [28][29][30].…”