There are many varying degrees and causes of hearing loss. In general, hearing loss is categorized by three basic types depending on the area of the ear or auditory system that is damaged.
Conductive Hearing Loss
Conductive hearing loss is caused by a mechanical problem along the route from noise in the environment to the inner ear. It could be a problem with one of the three small bones collectively called the ossicles (the stapes, malleus, and incus), or other parts of the ear that fail to conduct sound to the cochlea. Sometimes the ear drum is unable to vibrate sound properly. Conductive hearing loss can also be a result of fluid in the ear, congenital defects, a foreign body stuck in the ear, or even excess ear wax. Conductive hearing loss is often reversible.
Sensorineural Hearing Loss
Sensorineural hearing loss occurs when the inner ear, cochlea or auditory nerve itself is not functioning properly. It can also be caused when tiny hair-like projections inside the ear called cilia, which normally function to transmit sound through the ear, are damaged. This particular type of hearing loss is generally caused by damage from medications, birth injuries, or genetic factors. Less commonly this type of hearing loss can be caused by tumors, too much exposure to loud noises, head injuries, or other types of trauma. Sensorineural hearing loss cannot be corrected.
Mixed Hearing Loss
Mixed hearing loss is a term used to describe hearing loss caused by a combination of both conductive and sensorineural hearing loss.
Signs & Symptoms of Hearing Loss
- Conversations become increasingly difficult to understand, particularly if there is background noise.
- Difficulty understanding sound on the television.
- Fails to respond to name.
- Frequently asks for conversations to be repeated.
- Tinnitus, a constant ringing sound in one or both ears.
- While many sounds may be muted, others seem very loud and can be irritating.
Questions Your Doctor May Ask
- Do you have a family history of deafness or hearing loss?
- Do you have difficulty understanding conversations?
- Do family members complain that you keep the volume on the television too loud?
- Do you have a constant ringing or buzzing in the ears?
- Have you been frequently exposed to loud noises at work or recreationally?
- Do you have a history of ear infections?
Diagnosing Hearing Loss
Conductive hearing loss can often be diagnosed and even treated by an ENT physician. Sometimes an audiologist, a specialist in evaluating and treating hearing loss, is required, particularly in the case of sensorineural or mixed hearing loss.
Your doctor will conduct a physical examination beginning with two tests using a turning fork to discern the source of the deficit (conductive versus sensorineural). The doctor will also visualize the outer ear and then the inner ear and ear drum (also called the tympanic membrane), using an otoscope. He will be looking for excessive ear wax, foreign bodies that may be stuck inside the ear, infection, and any damage to the ear drum.
An audiologist can conduct a test of hearing tones. For this test, the patient is usually placed in a quiet sound room to ensure that background noise does not interfere with the test. A pair of headphones will deliver a variety of tones in different frequencies and volumes. This helps determine which range of tones and frequencies the patient can hear best. Another part of this test involves an instrument called a bone conductor. A bone conductor is a device that when placed behind the ear transmits sound by vibrating the bones of the ear. The bone conductor is beneficial in helping the audiologist determine what type of hearing loss you have.
Speech tests can also be conducted in a quiet sound room. The audiologist usually leaves the room and a series of words are played on a recording device. You will be asked to repeat the words. Different words will be played at varying tones and volumes.
To test middle ear function, an impedance test is used. The tone test will be repeated yet again while a probe placed in the ear will raise and lower the amount of pressure inside the ear.
Sometimes the results of these tests are charted on an audiogram. An audiogram is a chart which shows the degree of hearing loss in each ear.