Hearing is one of the five senses. It is a complex process of detecting sound and attaching meaning to it. The human ear responds to sounds that are very faint as well as to sounds that are very loud. The healthy human ear can also hear a wide range of pitches, ranging from 20HZ to 20,000HZ.
The ability to hear is critical to experiencing the world around us. To understand hearing loss, let’s first learn the basics of how a person can hear sound.
How We Hear:
The ear can be divided into three parts – the outer ear, the middle ear, and the inner ear.
- The OUTER EAR consists of the pinna, the ear canal, and the eardrum. Sound waves enter the pinna and travel down the ear canal, striking the eardrum and causing it to vibrate.
- The MIDDLE EAR is a space behind the eardrum that contains three small bones, called ossicles. They are the malleus, incus, and stapes. 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 converts the sound waves into electrical impulses, which are sent from the inner ear up the auditory nerve to the brain. The brain then interprets these electrical signals as sound. The brain, or the auditory cortex, processes the sound and interprets its meaning.
*Adapted from American Speech Language and Hearing Association (ASHA).