Objective The cochlear microphonic (CM) signal produced by the bat cochlear outer auditory hair cells contains information related to the movement of the cochlear basilar membrane. The aim of this study was to investigate the mechanism of bat cochlear nerve influence on echolocation by analyzing the relationship between frequency modulation (FM) bat CM signals and their received acoustic frequencies.Methods The CM signals of FM bats (Eptesicus and Pipistrellus) were recorded and analyzed in response to pure acoustic (tone burst) stimulation by placing a set of metal electrodes in the ventral cochlear nucleus.Results Two different species of FM bats (Eptesicus and Pipistrellus) exhibited CM mean frequency response curves during high sound pressure stimulation with a distinct concavity in the narrower specific frequency band vocalization. For Eptesicus, the CM RMS frequency response curves showed significant troughs on both sides of the terminal frequency (TF) of the first and second harmonics; moreover, these troughs were repeated at 15 kHz intervals from 15 kHz onwards; for Pipistrellus, the CM RMS frequency response curves showed significant troughs only on both sides of the first harmonic. The valleys are evident on both sides.Conclusion The relationship between the inhibition exhibited by the CM signal and the FM bat’s first and second harmonic TF reflects the fact that the cochlear nerve produces inhibition for specific frequencies, and this inhibition helps the bat to extract target localization information modulated to the vicinity of the TF.