What Do We Never Notice?

We will not notice bad smells after a time immersed. We will also put aside a loud noise if persistent. We still know of the smell or noise because we remember it from the original encounter.

What things do we never notice during our entire lives because we became used to them during our infancy, a point of time from which we have no memory? What things are always there from birth that we never notice because we got used to them just after we were born?