Hearing is one of our five senses. It is a complex process of picking up sound and attaching meaning to it. The ability to hear is critical to understanding the world around us.
The human ear is fully developed at birth and responds to sounds that are very faint as well as to sounds that are very loud. Even before birth, infants respond to sound.
The ear can be divided into three parts:
- The outer ear
- The middle ear
- The inner ear
The outer ear consists of the auricle, ear canal (external auditory canal) and eardrum (tympanic membrane). Sound travels down the ear canal, strikes the eardrum and causes it to move or vibrate.
The middle ear is a space behind the eardrum that contains three small bones, malleus, incus, stapes, also called ossicles. This chain of tiny bones is connected to the eardrum at one end and to an opening to the inner ear at the other end. Vibrations from the eardrum cause the ossicles to vibrate which, in turn, create movement of the fluid in the inner ear.
The movement of the fluid in the inner ear or cochlea, causes changes in the tiny structures located in the inner ear, called hair cells. This movement of the hair cells sends electric signals from the inner ear up the auditory nerve (also known as the hearing nerve) to the brain.
The brain then interprets these electrical signals as sound.