AMTAS: automated method for testing auditory sensitivity: validation studies

Three studies are reported assessing the validity of AMTAS, an automated method for obtaining an audiogram, including air- and bone-conduction thresholds (stimuli delivered by a forehead-placed transducer) with masking noise presented to the non-test ear. In Study 1, six subjects at each of three sites were tested using manual audiometry by two audiologists at each site. The mean differences between the audiograms for the paired audiologists provided a measure of the reliability of traditional audiometry. In Study 2, thirty subjects (5 normal hearing, 25 hearing impaired) were tested using AMTAS and manual audiometry. For air-conduction thresholds, AMTAS-manual differences were similar to inter-tester differences in Study 1, but for bone-conduction thresholds, the former were larger. Two possible sources of the greater differences were identified, (1) incorrect reference-equivalent threshold force levels for forehead bone conduction, and (2) a differential effect of middle-ear disease on forehead and mastoid bone-conduction thresholds. In Study 3, intersubject variability was studied for forehead and mastoid bone-conduction thresholds. The results indicate similar variability for the two placement sites.