Advanced Detection and Differential Diagnosis of Hearing Loss Using Otoacoustic Emissions

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Project Summary Most sensory hearing loss is diagnosed and treated with little distinction. Indeed, ”sensorineural hearing loss” is a catch-all term. However, promising results over the last few years suggest that otoacoustic emissions (OAEs) can distinguish among sensory hearing losses that appear similar by audiogram. OAEs are non- invasive indicators of cochlear health and dysfunction that can be recorded in normal hearers and those with up to moderate degrees of hearing impairment. Though they offer a non-invasive, pre-neural window into the cochlea, their application in the audiology clinic has stagnated over the last two decades despite significant advances in the laboratory. Current clinical utility of OAEs includes only the detection of hearing loss; nothing is learned about the etiology of the hearing loss once detected. This project proposes to translate into the audiology clinic a rapid, research-proven technique to evoke OAEs with sweeping tones, allowing for the efficient, near-simultaneous recording of the two basic OAE classes: emissions produced by cochlear nonlinearities such as the distortion-product OAE (DPOAE), and those produced by cochlear reflections such as the stimulus-frequency OAE (SFOAE). These two types of emissions elucidate distinct cochlear properties, and each is uniquely sensitive to different auditory pathologies and etiologies. Analyzing combined OAE outcomes produces new relational metrics that exploit the unique diagnostic information offered by both, which initiates differential diagnosis of sensory hearing loss. Additionally, our advanced OAE system has incorporated innovative calibration techniques that mitigate the effects of ear-canal standing-wave interference, a known source of undesirable variability. These advanced calibrations improve the test-retest reliability of emissions, which allows for more accurate serial monitoring of hearing status and an expanded high-frequency test range. In this project, we will: 1) integrate existing software modules that calibrate, measure, and analyze swept-tone OAEs into a cohesive and user-friendly software program for the interleaved recording of DPOAEs and SFOAEs; 2) analyze DPOAE and SFOAE measures in a combined fashion to detect and monitor hearing loss and perform differential diagnosis for hearing impairments of confirmed etiology; and 3) strategically pare down the Combined-OAE Profile and validate its performance in an independent group of participants to produce an abbreviated clinical test for the diagnosis of sensory hearing loss. These steps will modernize and advance OAE assessment well beyond the rudimentary goal of detecting hearing loss and provide a degree of diagnostic specificity that will facilitate personalized intervention for individuals with hearing loss.