Advanced Detection and Differential Diagnosis of Hearing Loss Using Otoacoustic Emissions

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.

Grant Number: 5R01DC018307-06
NIH Institute/Center: NIH
Principal Investigator: Carolina Abdala