The external and the middle ear conduct sound. When there is a problem in the external or middle ear, a conductive hearing impairment occurs. When the problem is in the inner ear, a sensorineural loss is the result. Difficulty in both the middle and inner ear results in a mixed hearing impairment (conductive and sensorineural impairment). Central hearing loss has more to do with the brain than the ear, and will be discussed only briefly.
Conductive hearing loss occurs when sound is not conducted efficiently through the ear canal, eardrum, or tiny bones of the middle ear, resulting in a reduction of the loudness of perceived sound. Conductive losses may result from earwax blocking the ear canal, fluid in the middle ear, middle ear infection, obstructions in the ear canal, perforations (hole) in the eardrum membrane, or disease of any of the three middle ear bones.
A person with conductive hearing loss may notice their ears seem to be full or plugged. This person may speak softly because they hear their own voice loudly. Crunchy foods, such as celery or carrots, seem very loud and this person may have to stop chewing to hear what is being said. All conductive hearing losses should be evaluated by an audiologist and a physician to explore medical and surgical options.
To demonstrate a conductive hearing loss, gently and safely close your ears with your fingers. This will give you the feeling of a conductive hearing loss you will feel plugged-up, and youll feel a little hearing impaired. Interestingly, some people may tell you they don't need hearing aids because they ONLY have a 30 decibel hearing loss. However, assuming you have normal hearing, when you plug your ears with your fingers, you will experience approximately a 25 decibel hearing loss and you will quickly realize that going through your day with that much hearing loss is quite irritating and disconcerting!
Sensorineural hearing loss is the most common type of hearing loss. More than 90 percent of all hearing aid wearers have sensorineural hearing loss. The most common causes of sensorineural hearing loss are age related changes and noise exposure. Sensorineural hearing loss may also result from disturbance of inner ear circulation, increased inner fluid pressure or from disturbances within the hearing nerve. Sensorineural hearing loss is also called "cochlear loss" and "inner ear loss" and is commonly called "nerve loss." Years ago, many professionals thought there was nothing that could be done for sensorineural hearing loss -- that is absolutely incorrect!!! There are many excellent options for patients with sensorineural hearing loss. People with sensorineural hearing loss typically report they can hear people speaking, but they cant understand what theyre saying. People with sensorineural hearing loss also complain that "everyone mumbles." They also usually hear better in quiet places and may have difficulty understanding what is said over the telephone.
Central hearing impairment occurs when auditory centers of the brain are affected by injury, disease, tumor, hereditary, or unknown causes. Loudness of sound is not necessarily affected, although understanding of speech, also thought of as the "clarity" of speech may be affected.
The audiologist and the physician work collaboratively to determine if hearing loss is "sensorineural" or "central."