by Neil Bauman, Ph.D.
A mother asked:
What is a conductive hearing loss?
There are two main kinds of hearing losses. One is called conductive and the other is called sensorineural.
Conductive losses are “mechanical” hearing losses, that is, something prevents the eardrum and/or the 3 tiny bones in the inner ear from vibrating freely. Conductive losses occur in the outer and middle ear.
In contrast, sensorineural hearing losses occur in the inner ear and are more “electro-chemical” in nature.
There are two common causes of conductive hearing losses. The first cause is wax or other “stuff” blocking the ear canal and preventing sound from getting to the eardrum. A variation of this would be wax or other material touching the eardrum preventing it from vibrating freely. Incidentally, a hole in the eardrum or scar tissue on the eardrum can also prevent it from vibrating as freely as before, thus resulting in some degree of conductive hearing loss.
The second common cause of conductive hearing losses is middle ear infections–often associated with getting a cold. When you have a middle ear infection, the middle ear, normally an air-filled cavity, fills up with a thick puss-like fluid. This fluid prevents the bones of the middle ear from vibrating freely. The result is reduced hearing of a conductive kind. The fancy medical term for a middle ear infection is “otitis media.”
Having your doctor clean your ear canals typically fixes the first kind of conductive loss.
Fixing the second cause is not as easy. Typically, once the cold goes away, the fluid in the middle ear slowly drains away via the Eustachian tube that connects the middle ear to the back of the throat. This process can take from a few days to a couple of months. When the fluid drains completely, hearing generally returns to normal again.
If this fluid won’t drain away on its own, doctors often intervene and put “tubes” in the ear drum to let the fluid drain into the ear canal.