We mostly tend to associate hearing loss with the elderly and when we encounter younger people who are hard of hearing, we assume they must be deaf since birth. But that’s hardly true. It’s possible for babies, children, teens or even adults to lose their hearing later in life, and sometimes suddenly.
It’s important to understand the type of hearing loss you are dealing with, before you can begin to even begin to understand its treatment. And before you can begin to understand the types of hearing loss, it’s important to understand how we hear sounds. Let’s have a look.
What’s In An Ear
A loss of hearing tends to occur when a part of our ear or the auditory system doesn’t work normally. To understand this better, let’s have a quick look at how the human ear looks and functions.
The Outer Ear is made up of our external ear (the pinna), the outer ear canal and the eardrum.
The Middle Ear has three small bones that transmit the vibrations of the eardrum to the inner ear. It also has a tube called the eustachian tube that connects the middle ear to the back of the nose.
The Inner Ear is made up of a fluid-filled organ called the cochlea that contains the nerves for hearing and semicircular canals called vestibules that help us keep our balance.
How Do We Hear?
When sound waves fall on the ears, they travel down the external ear canal and hit the eardrum that begins to vibrate, as a result. These vibrations are then passed on to the 3 small bones in the middle ear which then amplify the sound and send them to the fluid-filled organ called cochlea. Here the sound waves are converted into electrical signals which are transmitted to the brain using auditory nerves. And finally, the brain then interprets these signals as sound.
Types Of Hearing Loss
- Conductive Hearing Loss: This type of hearing loss occurs when there’s some kind of damage or an obstruction in the outer or middle ear that prevents sound from entering the inner ear. It may be temporary or permanent.
- Sensorineural Hearing Loss: This type permanent hearing loss occurs when there is damage to the cochlea in the inner ear or the auditory nerve itself which stops or weakens the transmission of nerve signals to the brain.
- Mixed Hearing Loss: Mixed hearing loss is a combination of sensorineural and conductive hearing loss.
- Auditory Processing Disorder: In this type of hearing disorder sound enters the ear normally, but because of the damage to the inner ear or the auditory nerve the information isn’t organized properly and the brain has trouble processing this information.
Apart from the types of hearing loss, there are also varying degrees of it, depending on what a person can and cannot hear.
Degrees Of Hearing Loss
- Mild Hearing Loss: A person with a mild hearing loss may hear some speech sounds but would find soft sounds hard to hear.
- Moderate Hearing Loss: A person with a moderate hearing loss can’t hear other people talking at normal levels.
- Severe Hearing Loss: A person with severe hearing loss can’t hear any speech when people talk at normal levels and can hear only some loud sounds.
- Profound Hearing Loss: A person with profound hearing loss doesn’t hear any speech and only very loud sounds.
Other Terms That You May Come Across
Here are a few terms you may see doctors and audiologists around you using often.
- Unilateral or Bilateral: Hearing loss can be in one ear (unilateral) or both ears (bilateral).
- Pre-lingual or Post-lingual: A Hearing loss that occurs before a child learns to talk is termed pre-lingual and if it happens after the person has learned to talk is called post-lingual hearing loss.
- Symmetrical or Asymmetrical: Hearing loss can be the same in both ears (symmetrical) or different in each ear (asymmetrical).
- Progressive or Sudden: Progressive hearing loss, as the name suggests, tends to worsen over time while sudden hearing loss happens quickly.
- Fluctuating or Stable: A hearing loss that gets better or worse with time is called fluctuating hearing loss and one that stays the same with time is called stable hearing loss.
- Congenital or Acquired: Hearing loss can be present from birth (Congenital hearing loss) or may appear later in life (Acquired or delayed-onset hearing loss).