I have read with interest your paper on Gekko palmatus. It is very good to see increased interest in lizard vocalizations and hearing and a broadening of the species investigated. I hope you and your group will be able to continue this work.
I do see a couple of serious problems with the paper, however, that obviously were not seen by the reviewers of your manuscript.
Firstly, the sound stimuli you used for the ABR measurements were not suitable for use at any frequencies below 1kHz. The rise time of the stimulus should not be shorter than about one cycle of the stimulus. Thus stimuli at, say, 0.2 kHz should have a rise time of 5ms. If you do not do this, the stimulus waveform becomes very distorted and you get spectral splatter - and that will get worse the further the frequency is removed from the ideal rise time. Then - unless you measure it - you do not know what the stimulus spectrum really looked like. Thus I do not trust your thresholds measured for stimuli below 1 kHz, since the spectral splatter will have provided energy at higher frequencies and the animals probably had better thresholds at those higher frequencies. Of course using long rise times makes it hard to measure synchronized responses such as the ABR. This is why in our paper on the pygopods (not pigopods), we did not attempt to use low-frequency stimuli. We used 500Hz, but changed the rise time from 1ms to 2ms (see our methods section).
You will also have noted that, contrary to the general pattern of frequency-following responses, the waveforms that you show in figure 3 for responses at 0.4 and 0.8 kHz do not correspond in frequency to that of the stimuli. This is probably another indicator of distorted stimuli with significant higher-frequency components.
Secondly, in our paper on pygopods we did in fact measure the sound pressures of the vocalizations. Thus we were able to show that at higher frequencies, the increase in the sound pressure of the vocalizations matched the loss of thresholds across the same frequency range, such that effectively, the sound level perceived by the animals stayed relatively constant across a broad range of frequencies.