The human ear is made up of three parts, the outer, middle, and inner ear. The outer ear consists of the pinner, which serves as protection for the delicate inner parts of the ear, and the external auditory meeters, the ear canal, which collects sound and direct sip towards the ear drum. The shape of the pinner also helps to detect where sounds are coming from in the vertical plane, that is from above or below the ear. The middle ear is an air-filled cavity located in the temporal area of the skull. It consists of the ear drum, the tympanic membrane. The ossicles and the eustachian tube. The tympanic membrane is concave with an area of between 60 and 90mm, and an average thickness of just 700mm, and it has a very rich blood supply. Sound waves enter the ear canal and strike the tympanic membrane, setting it in motion. The loud of the sound, the more the membrane moves. The middle ear also contains three small bones, known as the ossicles. These are connected in a chain across the middle ear, from the tympanic membrane to the entrance of the cochlear, called the oval window. The ossicles are called the malleus, the hammer, the incus, the anvil, and the stapes, the stirrup. The handle of the malleus is attached to the tympanic membrane, and the base of the stapes, known as the stapes footplate, sits loosely in the oval window of the cochlear, held in place by the annular ligament. The tympanic membrane vibrates in response to sound. The ear drum moves the malleus, which in turn moves the incus, and then the stapes, the footplate of which moves in and out of the oval window, and transfers the energy to the endolimp fluid in the cochlear. The inner ear has two distinct portions, the vestibular portion, concerned with balance, and the auditory portion, the cochlear, which is concerned with hearing. The vestibular portion is made up of three semicircular canals. Each canal has a swelling at one end, the ampulla, and two membranous sacs, the utricle, and the sacchial. These contain fluid and sensory cells, which move in response to head movements and travel to indicate the body's status. The vestibular system works in conjunction with the eyes, and the receptor cells in the joints of the body, to continuously maintain our balance. The cochlear appears as a coiled tube in the shape of a snail shell, with between two and a half and two and three quarter turns. It is wrapped around the acoustic portion of the auditory nerve. If we were to unravel the cochlear, it would be about 35 to 40mm long. It is split into three distinct sections, known as the scarlet vestibulee, scarlet media, and scarlet imparney. The scarlet vestibulee and the scarlet imparney contain perilimpt fluid. The scarlet media contains endolimpt fluid. The rice nurse membrane separates the scarlet vestibulee from the scarlet media, and the basilar membrane separates the scarlet media from the scarlet imparney. Along the basilar membrane are two types of sensory cells, or hair cells, called the outer and inner hair cells. These are arranged in their rows according to the frequency, or pitch, of sound they detect, and covered by the tectorial membrane. Each hair cell has tiny hair-like projections, called stereocilia, attached to them. When sound energy is transferred to the cochlear, the basilar membrane vibrates up and down, causing the outer hair cell stereocilia to shear on the tectorial membrane above. This shearing action causes the stereocilia to bend, which opens the iron gates, leading to chemical changes and a resulting electrical charge inside their cells. These charges make a neural impulse, which travels along the auditory nerve to the brain, and which is interpreted as sound. This complex mix of physical, chemical, and mechanical processes occurs almost instantaneously, and creates our perceptions of the sounds we hear in everyday life.