Acoustic reflex threshold tenth percentiles and functional hearing impairment.

This study addressed the issue of whether functional impairments can be identified or confirmed using tonal acoustic reflex thresholds (ARTs). Tonal ARTs from 74 ears with functional impairments were compared to 10th percentiles of the ARTs for normal and cochlear-impaired ears at 500 to 2000 Hz (Gelfand, Schwander, and Silman, 1990). Only one ear (5.3%) was correctly identified among the 19 ears in which all of the voluntary thresholds at 500 to 2000 Hz were < or = 55 dB HL. Acoustic reflex thresholds correctly identified functional losses in 70.9 percent, 78.6 percent, and 85.7 percent of the ears with voluntary thresholds > or = 60 dB HL at one, two, or three of these frequencies, respectively. The false positive rate was only 5 to 7 percent for a control group of 50 ears with genuine sensorineural hearing losses. The results indicate that tonal ARTs are an effective nonbehavioral tool for identifying or substantiating the presence of functional losses when thresholds are > or = 60 dB HL; however, ARTs cannot identify functional components when thresholds are < or = 55 dB HL.