Due to its ototoxic drug sensitivity and genomic similarity to human being,zebrafish has become an effective and economical model for drug/gene screening in auditory system.However,lack of approaches to quantify its hair-cell function has limited its application.Here we implemented two behavioral measurement systems for quantifying the hair cell functions.Acoustic startle response is an innate,reliable and robust behavior of zebrafish.An instrument system was implemented with a vibrator for delivering acoustic stimulus and a digital video system to record the larval movement.In each test,10 fish larvae were placed in a petri dish,which is stimulated by the vibrator underneath.Two features were extracted from the video to quantify the startle responses:the average moving distance and the number of fish that demonstrated typical C-shape bending after each stimulus.Vestibular ocular reflex(VOR)is a compensatory eye movement to stabilize retinal images.VOR is evoked by the vestibular receptors,so it can be used to evaluate vestibular and thus auditory function,since both systems share the same sensory cell,hair cell.An instrument system,including a rotational platform,a digital microscopic system and image processing software,was built to measure the gravity-induced linear VOR of zebrafish larvae.With the two systems,we first measured the fish behavior under different concentration of the ototoxic drug.6 pdf zebrafish larvae were treated with ototoxic drugs,neomycin and cisplatium,of different concentrations.Testing results from both systems showed that the magnitude of behavioral responses decreases with rising drug concentration and demonstrated the capability and possibility of both systems for ototoxicity drug screening.We also tested the impact of several gene manipulation to the hair cell functions using the VOR system.The results demonstrated significant difference between the wild type zebrafish larvae and the mutant.