We generally think of our ear as the external part- the” lug” we put our glasses on top of.  Technically this is called the Pinna and it’s one of three parts of our ear, which is one of three parts of our hearing system.
Sound waves (partially collected and directed by the pinna) travel down the ear canal to the eardrum causing it to vibrate. The eardrum in turn vibrates three tiny bones in the middle ear, which also amplify these vibrations and ultimately vibrate the oval window at the base of the cochlea which houses the inner ear.  Oval window vibrations cause tiny hair cells in the cochlea to bend or move and stimulate fibers of the hearing nerve which transmits the signal to the brain.
Outer ear (Pinna and ear canal): The pinna helps to direct sound waves down the ear canal to the eardrum (tympanic membrane). The length and shape of the ear canal help to protect the eardrum from insects, flying debris and foreign objects such as cotton buds.
Middle ear – The eardrum and three miniscule bones that physically amplify sound and transmit it to the inner ear by vibrating the oval window.
Inner ear – Shaped like a snail, but it works like a microphone. The inner ear converts physical movements (vibrations of the oval window)  into electrical signals- nerve impulses- that are sent to the auditory cortex in the brain where we actually hear sounds.