Audioscan automatic audiometry: theoretical basis and normative data

Audioscan automatic audiometry is a high resolution method to explore hearing thresholds in the 125 Hz-16 KHz range offering a resolution of 64 points per octave. This procedure makes it possible to study hearing threshold levels at intermediate frequencies which are not measured by conventional audiometry. As suggested in the literature, it is possible to identify hearing threshold notches, considered indicators of mild or subclinical cochlear pathology. In clinical practice, the use of a new audiometric technique requires affirmation of reliability, sensitivity and replicability in time. It also requires defining standard criteria for use in various otologic pathologies. The present study examined 50 normal hearing subjects with conventional audiometry and Audioscan (Essilor model) measurements. A standard acquisition protocol was followed where three Audioscan measurements were conducted per subject. Subjects with a history of acute otologic pathology and familiarity for genetic deafness were ruled out of the study. Multiple, pairwise correlation analyses of the audiometric and Audioscan responses indicate that: (1) there are no significant differences between threshold levels measured by Audioscan and conventional audiometry; (2) there are no significant variations in the hearing levels measured by three Audioscan retests. Three mean indicators of the threshold level have been defined, expressing Audioscan normality in three different frequency ranges. The data suggest that there are some difficulties in the subjectivity of the Audioscan method and some technical problems regarding the lower octave frequencies and these need to be addressed. The results obtained in this study confirmed reliability of the Audioscan in the mid and high frequencies. The definition of the standard mi criteria makes it easier to interpret the Audioscan measurements from cases presenting various otologic pathologies. Therefore, the plasticity and high detection sensitivity of hearing loss make the automatic Audioscan audiometry a useful clinical tool for diagnostic and/or preventive purposes.