Georg von Békésy discovered a 'place frequency map' in the cochlea where high frequencies stimulate the basal turn and low frequencies stimulate the apical end.

“So, he started performing these experiments in human temporal bones. So, they are collected when people die of unrelated causes and they donate their ears for study, and he was playing sounds of different frequencies, and noticed that those of high frequencies stimulated the basal turn, the basal portion of the cochlea, and those of low frequencies stimulated the high end.”