Wide Frequency Band Test of Hearing in Veterans

The goal of this research is to evaluate a comprehensive test battery of new wide-bandwidth, i.e., wideband (WB), acoustical tests of auditory function in the differential diagnosis of middle ear, cochlear and neural pathologies in a population of Veterans. WB tests refer to ear canal tests using sound responses measured from 0.2 kilohertz (kHz) to frequencies as high as 8 kHz, a bandwidth that is critical for speech perception. There will be tests in the battery for middle-ear assessment using power absorption, cochlear assessment using otoacoustic emissions (OAEs) and the acoustic stapedius reflex (ASR) using middle ear power absorption. Results will be compared with a standard single-frequency clinical immittance test battery routinely used in the assessment of auditory function in Veterans. Aim 1 seeks to evaluate the accuracy of the WB test battery in the differential diagnosis of middle-ear pathology and related conductive hearing loss by comparing the sensitivity and specificity of the WB battery to the traditional immittance battery for the following disorders common in Veterans: tympanic membrane perforation, serous otitis media, cholesteatoma, and otosclerosis. Aim 2 seeks to modify a WB ASR test to provide automatic detection of the ASR threshold for comparison with the traditional single-frequency ASR threshold. Aim 3 seeks to validate the use of Transient-evoked otoacoustic emission (TEOAE) and spontaneous otoacoustic emissions (SOAEs)tests in Veterans to assess cochlear status, and evaluate their test performance in classifying ears with normal hearing and sensorineural hearing loss. Finally, Aim 4 seeks to compare the diagnostic accuracy of the full WB test battery with the full single-frequency admittance test battery to detect any type of hearing loss including sensorineural, conductive and mixed. The hypothesis is that the WB test battery is more accurate than the traditional immittance test battery in identifying ears with normal auditory status and ears with a range of risks for auditory pathology.

Methods:

Subjects- Human subjects will be recruited for this study who have had a hearing evaluation from the VA Audiology Service at the Portland VA Medical Center and the H. Quillen VA Medical Center. These subjects will respond to flyers or be contacted from an IRB-approved human subject volunteer registry. Additional details regarding recruitment and selection criteria may be found in the next sections of the protocol. The investigators will recruit approximately equal numbers of subjects, with a total of 640. Data will be acquired at the two sites from a total of 190 adult subjects with normal hearing and 180 adult subjects with sensorineural hearing loss. These subjects will be recruited from three age groups: 20-39 years, 40-59 years and 60-79 years for age comparisons of normative middle-ear data. Data will also be acquired at both sites from 250 adult subjects with middle-ear disorders and/or conductive hearing loss from ages 20-89 years. Of this latter group, the investigators plan to enroll 50 subjects with tympanic membrane perforation, 50 subjects with serous otitis media, 50 subjects with cholesteatoma, 50 subjects with otosclerosis, and 50 subjects with unspecified middle-ear disorders. The investigators expect that approximately 20 subjects (from all groups, normal hearing, sensorineural hearing loss, and middle-ear disorders) will be lost as screen failures or will drop from the study, and thus, the investigators will recruit an additional 20 subjects to replace these. This brings the total planned number of subjects recruited for study to 640.

Testing- All subjects will receive the same clinical and WB test battery. Each subject will be tested in one laboratory visit. Subjects will be enrolled in this study that upon otoscopic inspection of their ear canals, have no active drainage from the ears, and have ear canals free of cerumen (wax) impaction, bilaterally. Subjects who are found to have draining ears or cerumen impaction will be referred for treatment. These individuals may be enrolled in the study following successful treatment for their conditions. All subjects will have a standard pure-tone air- and bone-conduction audiogram while comfortably seated in a sound-treated booth. Standard insert earphones and a bone-conduction vibrator will be used to present the sound stimuli. Next, speech audiometry will be completed and the speech reception thresholds, uncomfortable loudness test for speech, and speech recognition scores will be obtained. Then the subjects will have a standard immittance test battery consisting of a tympanogram and acoustic reflex threshold testing. Stimuli will not exceed a level of 100 decibels hearing level (dB HL). Finally, the wideband test battery will be performed with adults seated comfortably in a sound-treated booth. A small probe with a soft rubber tip will be inserted in the subject's ear canal, and the subject will be asked to remain quiet while sounds are presented to an ear via sound sources within the probe. Responses will be measured using a miniature microphone within the probe. The tests in the wideband battery are similar to the clinical admittance battery and include ambient absorbance, absorbance tympanometry and acoustic reflex threshold. The otoacoustic emission testing is a separate measurement of inner ear function typically conducted in the clinic using different equipment.