Audiogram, Acoustic Reflexes, and Evoked Otoacoustic Emissions

Audiologic testing in the form of pure-tone air-conduction and bone-conduction audiograms provides diagnostic information about the type of hearing loss (conductive, sensorineural, or mixed) and the degree of hearing loss and attendant communication difficulties. The addition of speech tests that use specific types of speech stimuli directly assesses the patient’s ability to hear and to understand speech. Acoustic reflex and reflex decay tests are used to evaluate the integrity of a complicated neural network involving not only the auditory tracts to and through the brain stem but also decussating pathways in the brain stem and the course of CN VII to the innervation of the stapedius muscle. EOAE tests provide an objective measurement of the peripheral hearing system from the external ear through the cochlear outer hair cells. They are useful screening tests for hearing in infants, in patients suspected of auditory neuropathy/dys-synchrony, and in patients suspected to have pseudohypacusis, that is, feigned or exaggerated hearing loss.