Reanalyzing auditory sensitivity: The functional audiogram as modeled by the bat detecting moth ear.

Auditory sensitivity has often been measured by identifying neural threshold in real time (online) which can introduce bias in the audiograms that are produced. This was tested by recording auditory nerve activity of the Notodontid moth Nadata gibbosa elicited by bat-like ultrasound and analyzing the response offline. The offline audiogram was compared to a published online audiogram showing that the bias introduced can result in a difference in both the best frequency of this moth ear and the audiogram shape. The offline neural threshold audiogram was then compared to audiograms produced using behavioral threshold definitions based on (1) spike period and (2) the latency to first spike, showing that audiograms produced using these theoretical behavioral definitions to have a similar shape. Finally, predictions on the distance at which Notodontid moths may evade bats using negative phonotaxis or the acoustic startle response are made, using the number of spikes elicited as a proxy for distance.