Introduction to Human Audition
The human auditory system allows the body to collect and interpret sound waves into meaningful messages. The main sensory organ responsible for the ability to hear is the ear, which can be broken down into the outer, middle, and inner ear. The inner ear contains the receptor cells necessary for both hearing and equilibrium maintenance. Human beings also have the special ability of being able to estimate where sounds have originated, commonly called sound localization.
Sensory Organs: The Ear
The ear is the main sensory organ of the auditory system. It performs the first processing of sound and houses all of the sensory receptors required for hearing. The ear's three divisions the outer, middle, and inner ear each have specialized functions that combine to allow us to hear .
The Structure of the Human Ear
1.Overview of Ear Structure :The outer ear is composed of the pinna, or ear lobe, and the external auditory canal. Both structures funnel sound waves towards the ear drum or tympanic membrane allowing it to vibrate. The pinna is also responsible for protecting the ear drum from damage. Modified sweat glands in the ear canal form ear wax.The middle ear is an air filled space located in the temporal bone of the skull. Air pressure is equalized in this space via the Eustachian tube which drains into the nasopharynx or the back of the throat and nose. There are three small bones, or ossicles, that are located adjacent to the tympanic membrane. The malleus, incus, and stapes are attached like a chain to the tympanic membrane and convert sound waves that vibrate the membrane into mechanical vibrations of the three bones. The stapes fills the oval window which is the connection to the inner ear.The inner has two functions; the first is hearing and the second is balance. It is a warren of tubes filled with fluid encased within the temporal bone of the skull. The bony tubes also contain a set of cell membrane lined tubes. The bony tubes are called the bony labyrinth filled with perilymph fluid, which the membranous labyrinth tubes are filed with endolymph. This is where the cells responsible for hearing are located (the hairy cells of Corti).