Recalibrating the perception of loudness: interaural transfer.

Previous research, using both magnitude-scaling and direct-comparison methods, has shown the perception of loudness to be contingent on the distribution of tonal stimuli varying in sound frequency as well as SPL: When a low-frequency signal, f1, is presented at low SPLs and a high-frequency signal, f2, at high SPLs, loudness at f1 is great relative that at f2; reversing the association of SPL with frequency reverses the loudness relation. These shifts in relative loudness, recently termed "recalibration" [Marks, J. Exp. Psychol: Hum. Percept. Perf. 20, 382-396 (1994)] [corrected], are consistent with the operation of frequency-specific, fatiguelike processes at f1 and f2. Experiment 1 combined both scaling (magnitude estimation) and matching (direct-comparison) methods and showed that exposing one ear to recalibrating stimuli (500 and 2500 Hz) led to substantial shifts not only in the ipsilateral ear but also in the contralateral ear (albeit smaller ones). Experiment 2 used a selective-exposure procedure and gave similar results. Thus the processes underlying recalibration of loudness appear to involve central mediation; consequently, it is possible that processes of auditory fatigue rely on central as well as peripheral mechanisms.