Philip F. Seitz
Ctr. for Auditory and Speech Sci., Gallaudet Univ., Washington, DC 20002-3695
Brad Rakerd
Michigan State Univ., East Lansing, MI 48824-1212
Individual differences in reaction time (RT) to subjectively comfortable, loud, and soft tones were assessed for ten young adult subjects with longstanding, less-than-profound sensorineural hearing losses and ten normal hearing controls. To support estimation of the sensory, central, and motor components of RT, subjects were also tested using an equivalent protocol with bright and dim visual stimuli. Subjects with normal hearing listened to 500-Hz tones at fixed intensities that pilot testing established as corresponding to comfortable, loud, and soft levels. Prior to RT testing, subjects with hearing losses individually adjusted tone intensity to ``most comfortable,'' ``very loud but not painful,'' and ``very soft but definitely audible'' levels. Results show larger modality-dependent and level-dependent individual differences in RT than have been previously noted in the literature, pointing up a need for individual subject baselines in cognitive experiments that use RT as a dependent variable. Results also indicate that the typically small range between threshold and pain in listeners with hearing losses is, with respect to RT, functionally equivalent to larger ranges in normal hearing listeners in some individuals but not in others. [Work supported by NIH-NIDCD.]