FIG. 5.

Pooled monophasic 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 desensitisation (A) and sensitisation (E) occurred, with desensitisations dominating. A simulated initial OP below (black symbol, B) or above (F) the inflection point on the Boltzmann function can produce a monophasic desensitisation (D) or sensitisation (H), if the first derivative (i.e. the slope) of the Boltzmann function (C, G) is used to simulate outer hair cell efficiency. D, H: outer hair cell efficiency as a function of an OP change following a damped oscillation, in hyperpolarising direction on the MET transducer function and back (i.e. corresponding to a movement of the organ of Corti towards scala tympani and back). Monophasic sensitisation occurred in subjects AK, JU, ML, PP and RM, and monophasic desensitisations occurred in subjects AI, AK, CF, CB, KF, LS, ML, NH, PW, RS, SW, SL, TH and TS. In A and E, 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.