Another way of describing the frequency is through musical pitch. We do not perceive frequency changes linearly. Going from 110h hz to 220 hz will not sound the same as going from 220 hz to 330 hz, even if the distance between the sounds is 110 hz in both cases! This is because we hear pitch differences as proportions, not as absolute differences. So every time the frequency doubles, we hear it as the same note one octave higher.