Development of sensorineural hearing loss is examined by measuring electromtile activity of isolated cochlear, mammalian outer hair cells. Sensorineural hearing loss of Meniere’s disease, otitis media and ototoxicity origin are modelled in guinea pigs by induction of endolymphatic hydrops and otitis with effusion. Electromotile performance of isolated outer hair cells from these animals is correlated with that of the objectively determined (otoacoustic emission, electrocochleography) hearing function of the animals and human patients. Comparing to the in vivo animal models, hair cell motor function (electromotility) is also measured in models of in vitro treatment of isolated outer hair cells by high potassium containing fluids, efferent neurotransmitters and regulators of the intracellular calcium concentration. Correlation of sensorineural hearing loss, electromotility and stiffness of the hair cell lateral membrane is aimed to establish. Modification of the intracellalar calcium oscillations and the calcium dependent phosphorylating enzyme machinary in the outer hair cells are studied as to antagonize the sensorineural hearing loss due to damage of the motor function.