The degree of deafness is measured by testing both loudness (decibels) and pitch (frequency) and plotting responses onto a graph called an audiogram.
What we hear – or don’t hear – is then broken into categories, which are:
Normal hearing: 0-25 decibels
Mild hearing loss: 26-40 decibels
Moderate hearing loss: 41-55 decibels
Moderately severe: 56-70 decibels
Severe deafness: 71-90 decibels
Profound deafness: greater than 90 decibels
Someone who is severely or profoundly deaf is said to have significant deafness. Even very loud noises are heard only faintly. Hearing aids may enable the wearer to hear more of the sound; however, it is important to be aware that hearing aids do not correct sound. Therefore, even though a hearing aid user may hear the sound, s/he may not be able to make sense of what is heard.
Click here to for a simulation of deafness.