Because the cochlea is a minute and delicate organ embedded in thick bone it has been impossible to make direct observations of the events taking place in the inner ear in response to acoustic stimuli. For this reason the dynamic behavior of the ear has been considerably neglected in the formulation of theories of the analysis for pitch. However, a great deal of experimental evidence has come forward during the last ten years which clearly sets down certain fundamentals on which the final picture will be based. In this paper I have attempted to tie all this evidence together into a uniform pattern of thought, so as to present a broad functional analysis of the processes responsible for the subjective discrimination of sound. COCHLEAR MECHANICS Although little is known of the physical constants of the inner ear, reasonable assumptions can be made regarding the nature of such factors as the