Dogs hear through a combination of the auricle, external ear canal, eardrum, bony tympanic cavity and the inner ear. The auricle is the visible outside portion of a dogs ear that is covered in fur. The auricle is attached using over 18 muscles, whereas humans have only six.
These additional muscles allow the dog to independently rotate each of their ears in different directions. Sound waves are captured and amplified by the auricles cone shape and passed down into the external ear. The external ear canal funnels these sound waves into the middle ear, which houses the eardrum and the bony tympanic cavity. The sound waves vibrate the eardrum, which in turn vibrates the bones that are suspended in the tympanic cavity. These bones are called the malleus, stapes and incus, or more commonly known as the hammer, the stirrup and the anvil due to their characteristic shapes. These bones form a bridge from the eardrum, across the tympanic cavity, and to the window of the inner ear.
The first part of the inner ear cavity is made up of a maze of thin mucus covered membranes that receive the vibrations from the middle ear and pass them into a spiral tube called the cochlea. The vibrations then trigger nerves along the cochlea that transmit electrical pulses to the dog's brain and help it interpret what sound it is listening to.