Types of Hearing Loss

The Three Parts of the Ear

The ear is divided into three parts that send information to the brain.

Outer Ear

The outer ear includes the pinna, ear canal and eardrum. The pinna is the part of the ear that we see. It collects and localizes sound vibrations and guide the vibrations to the ear canal. Sound then travels through the ear canal, hits the eardrum and then causes the eardrum to move.

Middle Ear

The middle ear is an air-filled space that includes three very small bones (the malleus, incus and stapes) that are connected to each other. They are collectively attached at one end to the eardrum and at the other end to the inner ear. The movement of the eardrum causes the bones to vibrate, which then causes movement in the inner ear.

Inner Ear

The inner ear includes two functionally separate sections: The cochlea is the hearing section, and the semicircular canals are the vestibular or balance part. The balance portion helps with the sense of acceleration and deceleration of both rotational and linear motion. The cochlea is a fluid-filled bony coiled canal, which is shaped like a snail. The movement of the fluid in the cochlea causes the movement of tiny hair cells, called cilia, in the cochlea. These hair cells respond to specific sound pitches and through their movement send electrical signals through the hearing (auditory) nerve to the brain.   

The auditory processing centers of the brain then use the electrical signals to interpret the meaning of the sound.

Types of Hearing Loss

Hearing loss can occur at any age. It may be caused by many different factors and is categorized by the part of the auditory system that is damaged. Please review “How We Hear” prior to reading this section. It is important to understand the basic anatomy of the ear prior to trying to understand the types of hearing loss. The three basic types of hearing loss are sensorineural, conductive and mixed.

Sensorineural Hearing Loss

Sensorineural hearing loss involves damage to the inner ear, the cochlea, or to the actual auditory nerve pathways to the brain. It is the most common type of hearing loss, involving about 90% of all people with hearing impairment. This type of loss is often called “nerve deafness” though most causes of hearing loss involve the inner ear and not the hearing nerve. This type of hearing loss usually is not medically or surgically treatable. Most people with a sensorineural hearing loss will benefit from hearing aids, and some individuals with severe hearing loss may be helped by a cochlear implant.

Conductive Hearing Loss

Conductive hearing loss involves damage to the outer ear or the middle ear. This type of loss involves a reduction in the volume of sound that is transferred to the inner ear. Conductive loss is often treatable medically or surgically. Common causes of conductive hearing loss are fluid blockage in the middle ear or wax obstructing the ear canal. This is the most common type of hearing loss for children.

Mixed Hearing Loss

Mixed hearing loss is a combination of both sensorineural hearing loss and conductive hearing loss.