FIG. 6.

Pooled biphasic changes of hearing thresholds probed with 1, 2 and 4 kHz after LF sound exposure relative to the mean of the pre-exposure period. Both initial sensitisation (A) and desensitisation (E) occur. A simulated initial OP above (black symbol, B) or below (F) the inflection point on the Boltzmann function can produce a biphasic change with initial sensitisation (D) or desensitisation (H). D, H: as in Fig. 5, with a sinusoidal OP change. Biphasic changes with initial sensitisation occurred in subjects FK and RS, with initial desensitisation in the subjects AI, CF and KB. Solid lines = 1 kHz probe tone, dashed-dotted line = 2 kHz, dotted line = 4 kHz. Dashed lines in B, C, F and G indicate the range of the OP shift.