Sensorineural Hearing Loss
Your outer ear, middle ear, inner ear and brain all play a part in the complex process that results in the sounds that you hear. Deep within your middle ear is a coil-shaped canal called the cochlea (kok-lee-uh). Tiny hairs within the cochlea play a delicate and critical role in your hearing clarity. Put simply, their response to sound waves creates nerve signals, which are transmitted by nerve fibers to your brain. Your brain then interprets those nerve signals as sound.
Over time, i.e., with age, these tiny hairs and nerve fibers can become damaged or die. The hair cells do not regenerate, so as the number of functioning hairs decreases, hearing clarity decreases. The resulting hearing loss is irreversible but can be helped with properly prescribed hearing aids and assistive listening devices.
The two most common types of sensorineural hearing loss:
- Presbycusis - Age-Related Hearing Loss and
- Noise-Induced Hearing Loss.
Congenital hearing loss in children can also result in sensorineural hearing loss.
Presbycusis - Age-Related Hearing Loss
Presbycusis (prĕz'bĭ-kyū'sĭs), also known as age-related hearing loss, is the cumulative effect of aging on hearing. It is a gradual loss that happens over time – so gradual in fact that people with presbycusis may not realize that their hearing is diminishing. Signs of this loss include:
- Difficulty hearing high-frequency sounds like speech.
- Challenges in understanding conversations in noisy settings
- Even in quiet settings people's voices sound mumbled or slurred.
Age-related hearing loss is very common: affecting 1/3 of people between 65 and 75 years and up to 1/2 of people 75 and over.
While environmental exposure to noise (such as power tools, loud music — see Noise-Induced Hearing Loss below) contributes to presbycusis, up to half of presbycusis is genetically determined.
Although presbycusis actually begins its affect on hearing in one’s early 20's, it is not until people are in their 40's and 50's that they start to notice a change in their hearing.
Noise Induced Hearing Loss
Essentially, noise-induced hearing loss occurs when hearing is damaged over time by exposure to loud noise without proper hearing protection. Loud music, power tools, construction noise, lawnmowers, firearms, and recreation noise, e.g., motorcycles and speedboats, all take their toll on your hearing clarity—words aren't clear or music doesn't sound as nice as it used to because you're now missing the full frequency or range of sound.