、。
Comparing a dog's sense of hearing to a human's, it's vastly superior.
Literal
Dog [genitive-の] hearing [genitive-の] sensitivity [object-を] human [with-と] compare-[when-ると], far-far above is.
An analytical comparison. はるかに ('far,' 'vastly,' 'by a wide margin') is an adverb used for comparisons that aren't close — it intensifies a comparison beyond just 'more.' The pattern [X]を[Y]と比べると ('comparing X to Y') uses the と as a comparison marker ('with') and ると as the conditional/temporal 'when.' Together: 'when comparing X with Y, (then X is...)' 上だ ('is above,' 'is higher') is an idiomatic comparative — literally 'is up,' used figuratively for 'superior,' 'more advanced,' 'better.' 敏感さ ('sensitivity') is the ~さ nominalizer attached to 敏感 ('sensitive'), converting the な-adjective into a noun.