"a dynamic range of about 120 dB"
Sound of a jackhammer at 1m has sound pressure level of approximately 100dB (relative to 20 uPa). Leaves rustling gently in the wind have sound pressure level about 10dB. If our hearing actually had 120dB dynamic range we'd be able to easily hear the rustling of the leaves while jackhammer is pounding right next to us, not to speak of normal conversation which roughly has level of 50-60dB.
As an analogy to radio equipment we might say that human ears have automatic gain control which spans 120dB (or as audio comparison we can adjust the volume on that span) but the range which we can discern two sources (the instantaneous dynamic range) is about 30dB or less.
Also about the frequency resolution of the ear vs the eyes the bandwidth are on a completely different scale. Visible light spans about 380THz which means that the bandwidth of that signal is 19 250 000 000 times the bandwidth spanned by our ears. You cannot do just simple octave based comparison as the amount of information is not dependent on the amount of octaves but only on bandwidth. You are correct in the sense that the eye uses this information in quite limited fashion, however the actual processing is not on normal frequency domain but on spatial domain (eye is not just one sensor but craploads of them).
As an analogy to radio equipment we might say that human ears have automatic gain control which spans 120dB (or as audio comparison we can adjust the volume on that span) but the range which we can discern two sources (the instantaneous dynamic range) is about 30dB or less.
Also about the frequency resolution of the ear vs the eyes the bandwidth are on a completely different scale. Visible light spans about 380THz which means that the bandwidth of that signal is 19 250 000 000 times the bandwidth spanned by our ears. You cannot do just simple octave based comparison as the amount of information is not dependent on the amount of octaves but only on bandwidth. You are correct in the sense that the eye uses this information in quite limited fashion, however the actual processing is not on normal frequency domain but on spatial domain (eye is not just one sensor but craploads of them).