Otoreflectance (OR) is a new class of hearing test instruments utilizing acoustic signals presented and recorded in the ear canal. OR instruments address limitations in existing screening and diagnostic instruments in such areas as: (1) detecting otitis media, (2) predicting conductive hearing loss, (3) augmenting the newborn hearing screening protocol to test for middle-ear dysfunction, and (4) the general assessment of middle-ear functioning at frequencies important for speech perception. OR provides calibrated measurements over a frequency range from approximately 0.25 to 8 kHz of such transfer functions as reflectance and admittance, and the power absorbed by the ear canal and middle ear. Energy reflectance and absorbed power are OR functions that are relatively insensitive to the position of the probe in the ear canal. This property may allow clinical interpretation of these functions at moderate and high frequencies at which the tympanometric admittance, which is sensitive to probe position, becomes difficult to interpret. One proposed class of OR instruments can be used with probes similar to otoacoustic emission probes to screen middle-ear functioning in several seconds at ambient pressure in the ear canal. Such rapidly performed measurements at ambient pressure may provide a test of middle-ear dysfunction in newborn hearing screening programs, and a test to screen for conductive hearing loss in children at risk for otitis media with effusion. Another proposed class of OR instruments, for which a static pressure pump will be added to the probe system, will be used to measured reflectance, admittance and absorbed power as functions of both frequency and static pressure in the ear canal. Such OR tympanometry instruments may have general audiological and screening utility for diagnosing middle-ear pathology due to the fact that the energy reflectance tympanogram has more orderly patterns at moderate and high frequencies than multifrequency tympanometers based only on admittance. A third proposed class of OR instruments may provide a sensitive test of the acoustic reflex threshold by measuring the wideband shift in OR responses elicited by a contralateral or ipsilateral activator sound. A protocol to measure supra-threshold reflex decay may provide additional wideband information that is unavailable in clinical reflex testing.
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