Fig. 4.

Reproducibility of umbo vibration responses from one day to the next, with and without placement of a reflector. The measurements on the first day were made without placement of a reflector on the umbo, whereas a reflector was placed for the measurements 24 h later. (A) Amplitude spectra for two-tone stimulation with f₂ = 5.0 kHz, f₁ = 4.2 kHz, L₂ = 55 dB SPL, and L₁ = 61 dB SPL. The gray shaded line represents measurements without reflector placement on the first day. The black line represents measurements with reflector placement 24 h later. Notice that (i) all three signals superimpose and (ii) there is a (small) improvement of SNR with the reflector (up to 10 dB below 3.6 kHz). (B) Displacement amplitude responses of the umbo expressed for a SPL of 60 dB. The measurements shown are without reflector placement on the first day (●) and with reflector placement 24 h later (▵). Notice that the reproducibility is better than 1 dB up to 7 kHz. (Subject identifier: SK.)