A hydrodynamic theory of acoustical action of the cochlea is developed, taking the following factors into account: density and viscosity of the perilymph, impedance of the cochlear duct, and cross-section of the cochlear canal. On the basis of this theory it is deduced that a maximum of vibration can occur without resonance and likewise without any form of wave reflection. For this case no accumulation of energy is necessary and therefore there is the possibility of a frequency analysis with aperiodic damping. Such behavior corresponds well with the experimentally detd. action of the ear, which for a long while seemed to be paradoxical.