Types

Hearing loss is divided into categories depending on the severity of the condition. Moderate hearing loss is defined as a loss of between 41 and 55 decibels. Moderately severe hearing loss is a loss of between 56 and 70 decibels. Severe hearing loss is a loss of between 71 and 90 decibels.

Causes

Aging and the weakening of the inner ear's sensitivity are the primary causes of hearing loss. The condition is also commonly caused by frequent exposure to unhealthy amounts of noise. For example, people who work on airport runways wear ear muffs to prevent hearing loss.

Unilateral Loss

This is defined as the loss of hearing in one ear, as opposed to both ears. Those affected often cannot properly distinguish noise directions or background noise.

Deafness

Deafness is considered to be a different condition from being hearing impaired, particularly by the deaf community. Deafness is the complete loss of hearing in both ears, while hearing impaired persons are often referred to as "hard of hearing."

Solutions

Hearing aids have been around for decades and are small devices that rest within the ear and amplify incoming sound. There are also cochlear implants, which involve a surgical procedure that can alleviate deafness in certain patients.

Source:

EEOC - Deafness

American Hearing

Hard of Hearing Advocates