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HOW DO WE HEAR?

Hearing is one of the 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 a fully developed part of our bodies at birth and responds to sounds that are very faint as well as sounds that are very loud. Even before birth, infants respond to sound.

The ear can be divided into three parts leading up to the brain – the outer ear, middle ear and the inner ear.


The outer ear consists of the ear canal and eardrum. Sound travels down the ear canal, striking the eardrum and causing it to move or vibrate.


The middle ear is a space behind the eardrum that contains three small bones 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, creates movement of the fluid in the inner ear.

Movement of the fluid in the inner ear, or cochlea, causes changes in tiny structures 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.

WHAT IS HEARING LOSS?

Hearing loss is a sudden or gradual decrease in how well you can hear. Depending on the cause, it can be mild or severe, temporary or permanent.


Congenital hearing loss means you are born without hearing.

Gradual hearing loss happens over time and can affect people of all ages.


If you have hearing loss, you may not be aware of it, especially if it has happened over time. Your family members or friends may notice that you're having trouble understanding what others are saying.

We measure hearing loss on a graph called an audiogram.

WHAT CAUSES HEARING LOSS?

In adults, the most common causes of hearing loss are:

Noise. Noise-induced hearing loss can happen slowly over time. Being exposed to everyday noises, such as listening to very loud music or using a lawn mower, can damage the structures of the inner ear, leading to hearing loss over many years. Sudden, loud noises, such as an explosion, can damage your hearing.


Age. In age-related hearing loss, changes in the inner ear that happen as you get older cause a slow but steady hearing loss. The loss may be mild or severe, and it is always permanent. 


Other causes of hearing loss include earwax buildup, an object in the ear, injury to the ear or head, an ear infection, a hole in your eardrum, trauma or other conditions that affect the middle ear, inner ear or brain.



The information above is non-diagnostic and is presented for information purposes only.

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