Types of Hearing Loss
Hearing loss can be divided into two basic types, conductive and sensorineural. Mixed loss is a combination of the two basic types. There are other types of hearing losses that cannot be categorized into the two basic types as they occur beyond the hearing organ and are a brain processing malfunction.
The vast majority of diagnosed hearing losses are related to the neural process of sensation – sensorineural hearing loss.
Conductive Hearing Loss
Conductive hearing loss is caused by anything that interferes with the transmission of sound from the outer to the inner ear.
Possible causes of conductive hearing losses include:
- compacted wax
- perforation of the eardrum
- glue ear
- dislocation or fusion of the bones in the middle ear
- foreign object in the ear
- malformation from birth of outer or middle ear
- sporting injury
- head injury
Conductive hearing losses, can be viewed as a mechanical problem and are often treatable medically with or without surgery. Depending upon the cause, conductive hearing loss can sometimes be a temporary problem. If the problem cannot be sufficiently treated medically, conductive hearing loss responds very well to hearing aid amplification. This is due to the inner ear still working well but requiring an increase in volume / amplification. This is simply provided by the use of a digital hearing aid.
Sensorineural Hearing Loss
Possible causes of sensorineural hearing loss include:
- Presbyacusis (Age related hearing loss)
- Noise Induced Hearing Loss (NIHL)
- Meneire’s Disease
- Viral Infections such as Measles, Meningitis or Chicken Pox
- Maternal Rubella
- Acoustic Neuroma
- Vascular episodes eg. a stroke
- Physical damage to the inner ear via an injury
- Side affect of certain drugs
Sensorineural hearing losses can be likened to an electrical problem, which can be more difficult to deal with than a pure conductive (mechanical) problem. There are often other side effects and symptoms related to these types of losses including tinnitus, intolerance to loud sounds and distortion. Most sensorineural problems are difficult to treat medically but with sophisticated digital hearing aid technology we can help overcome many of these complications. When setting up a hearing aid for sensorineural loss we need to provide a balance of volume and clarity resulting in the clearest sound possible.
Other Types of Hearing Loss
Mixed Hearing Loss
The third hearing type is a mixed hearing loss and this occurs when you have both conductive and sensorineural losses in the same ear. The hearing aids to help this type of loss require a superior technology than that used for pure conductive hearing loss.
Central Hearing Loss
A central hearing loss is when there is a malfunction of the brain or neural pathways to the brain. Ordinarily, interpreting speech is a complex task and with central hearing loss the person can hear perfectly well but will have trouble interpreting or understanding what is being said. One of the conditions of central hearing loss is “central auditory processing disorder” which affects a person’s inability to filter out competing auditory signals. People with central auditory processing disorders have difficulties that include:
- Problems “hearing” when there are several conversations going on
- Inability to read or study with the radio or television on
- Problems reading if someone turns on a vacuum cleaner or air conditioner near them
- Generally missing the first sentence from people talking to them if they are involved in an auditory attention task (such as watching television)
These difficulties may lead the suffering or family and friends into believing that they have a hearing loss but infact the ear is functioning normally and a hearing test result will be normal. People with this condition may also develop hearing loss from other causes and this can make it even more difficult for them to function under everyday circumstances.
There is no specific treatment for central auditory processing disorders other than educating the person, family and friends to control the listening environment. Using hearing devices can help by cleaning up the sound and reducing noise signals and thus focusing attention on the main sound source. For example, a child with central auditory processing disorder in a classroom will need to sit in a good position near to the teacher and be given more time for instructions and explanations. It is not a reflection of child’s intelligence, however, the slower processing speed can have a significant effect on their success at school.