We administered a battery of both behavioral and electrophysiologic measures to a
pair of fraternal twin girls, one of whom exhibited symptoms consistent with an auditory
processing disorder. Both twins were within normal limits on standardized tests of
cognitive and language skills. Basic audiometric measures, as well as behavioral tests
of simultaneous masking, backward masking, gap detection, and frequency-sweep discrimination,
showed little difference between the twins. Significant differences, however, were
evident on event-related potentials (ERPs) in response to both within-channel and
across-channel gap detection tasks. Substantial differences were also noted for ERPs
to both linguistic and nonlinguistic targets in dichotic listening paradigms. The
pattern of electrophysiologic results was consistent with a deficit in the efficiency
of interhemispheric transfer of auditory information. A possible reason for the greater
effectiveness of electrophysiologic over behavioral measures is discussed.
Key Words
Auditory processing disorder - backward masking - dichotic listening - event-related
potential - gap detection - interhemispheric transfer
