Question
What percentage rollover would be considered positive when doing speech discrimination testing at suprathreshold levels?
Answer
Speech recognition rollover is one of the special tests that, in the pre-ABR and pre-MRI era, comprised the battery of tests that were helpful for screening for retrocochlear pathology. ABR significantly increased the sensitivity of auditory testing to VIIIth nerve lesions and MRI was found to be significantly more sensitive than ABR. As a result, acoustic neuromas and other lesions of the VIIIth nerve and cerebellopontine angle are now typically under a centimeter in diameter at detection and often under 0.5 cm. Before ABR and MRI, two-, three-, and four-cm tumors at detection were common. Consequently, those special tests represent an important development in the history of diagnostic audiology but are no longer in widespread use.
There are two classic papers on speech recognition rollover for detection of retrocochlear pathology. Jerger and Jerger (1971) measured speech recognition rollover for 41 subjects with cochlear hearing loss and 16 subjects with retrocochlear pathologies. Their important observation was that when rollover was expressed as a difference (maximum score - minimum score), there was poor separation between groups. But when the difference was expressed as a proportion of the maximum score, there was nearly complete separation between patients with cochlear hearing loss and those with VIII nerve pathology. Dirks et al. (1977) reported results on 89 ears of 59 subjects with cochlear loss and 8 ears of 7 subjects with retrocochlear loss. Their results agreed closely with those of Jerger and Jerger. In both studies a "rollover index" of 0.45 provided excellent separation of the two groups.
References
Jerger J, Jerger S (1971). Diagnostic significance of PB word functions. Arch Otolaryng 93, 573-580.
Dirks DD, Kamm C, Bower D, Betsworth A (1977). Use of performance-intensity functions for diagnosis. J Speech Hear Dis 42, 408-415.
Robert H. Margolis (b. Lorain, Ohio, 29 June 1946) earned bachelor's and master's degrees from Kent State University (1968, 1969) and a Ph.D. degree from the University of Iowa (1974). After a post-doctoral research fellowship at the University of Wisconsin, he joined the faculty of the UCLA Medical School in 1975. In 1980, he was appointed associate professor of communication sciences and disorders and director of the Gebbie Hearing Clinic at Syracuse University. In 1988 he became professor and director of audiology at the University of Minnesota Medical School.
Dr. Margolis has over 120 publications in scientific and clinical journals and textbooks. His research has focused on development of methods for evaluating disorders of hearing. He has been awarded research grants from the Deafness Research Foundation, and the National Institutes of Health. He has served as president of the Minnesota Academy of Audiology, the International Hearing Foundation, and the Minneapolis- University Rotary Club. He has been awarded the Honors of the Association by the Minnesota Academy of Audiology, the Humanitarian Award by the American Academy of Audiology, the Editor's Award by the Journal of the American Academy of Audiology, the Rotarian of the Year award by the Minneapolis-University Rotary Club, the Larry Mauldin Award for Excellence in Education in Audiology, and an Honorary Membership by the Vitacura Rotary Club (Santiago, Chile).
Margolis lives in Arden Hills, Minnesota with his wife, Janet, and two daughters, Jane and Brittany. He coaches girls' basketball and softball and enjoys tennis and fishing.
