There are two ways in which a dogs hearing is
superior to a humans; 1) they can hear a wider
range of high pitch sounds and 2) they can hear
further distances. The increased range of
frequencies is due to differences in the length
and shape of the cochlea; a coiled cavity in our
inner ear lined with cells that translate high and
low frequencies into nerve impulses.
Dogs can hear further distances because the
shape of the outer ear. Ears act as a funnel to
capture sound waves. A dogs ears are larger and
can swivel in the direction of a sound thus
maximizing the sound waves collected. As you
could imagine dogs with pointed ears (versus the
cute floppy ears) have better hearing.
And for the cat lover, fun fact: Cats can hear
even better than dogs!