Hearing

Hearing loss that takes place slowly as you age (presbycusis) prevails. About one-third of individuals in the United States in between the ages of 65 and 75 have some degree of hearing loss. For those older than 75, that number is approximately 1 in 2. Hearing loss is defined as one of three types: Conductive (includes external or middle ear) Sensorineural (includes inner ear) Combined (mix of the two) Aging and chronic direct exposure to loud noises both contribute to hearing loss.

You can’t reverse most kinds of hearing loss. However, you and your medical professional or a hearing specialist can take steps to improve what you hear. The ear is made up of three main parts: the outer ear, middle ear and inner ear. Each area is made up of structures that play distinct functions in the process of transforming sound waves into signals that go to the brain.

The cup-shaped pinna (PIN-uh) gathers acoustic waves from the environment and directs them into the ear canal. The middle ear is an air-filled cavity that holds a chain of three bones: the hammer, anvil and stirrup. These bones are separated from the outer ear by the eardrum (tympanic membrane), which when struck by an acoustic wave, vibrates.

The tube opens and closes at the throat end to match the pressure in the middle ear with that of the environment and drain fluids. Equal pressure on both sides of the eardrum is essential for normal vibration of the eardrum. The middle ear consists of three small bones: Hammer (malleus) connected to eardrum Anvil (incus) in the middle of the chain of bones Stirrup (stapes) connected to the membrane-covered opening that connects the middle ear with the inner ear (oval window) The vibration of the eardrum sets off a chain of vibrations through the bones.

This boost in force is required to transfer the energy of the acoustic wave to the fluid of the inner ear. The inner ear includes a group of interconnected, fluid-filled chambers. The snail-shaped chamber, called the cochlea (KOK-lee-uh), plays a role in hearing. Sound vibrations from the bones of the middle ear are moved to the fluids of the cochlea.