Types & Causes of Hearing Loss

There are three primary hearing loss categories: sensorineural, conductive, and mixed.

Sensorineural hearing loss occurs when damage occurs to the tiny nerves (hair cells) within the cochlea or along the auditory nerve. Sensorineural hearing loss is permanent and typically there are no medical or surgical options to correct it. The primary treatment for this type of hearing loss is the use of hearing aids. The sooner amplification is used the better the overall outcome. Research shows delaying the use of hearing aids results in decreased overall benefits. In some cases the benefit of the hearing aid is so limited cochlear implantation is suggested.

The most common sensorineural hearing loss is a high-frequency hearing loss, typically associated with environmental noise exposure and/pr the aging process. .This type of hearing loss may be difficult for patients to accept because it occurs slowly over many years. People with high-frequency sensorineural hearing loss often note they can hear, but they cannot distinguish the words. They may say “people don’t speak as clearly as they used to…”
Conductive hearing loss results from a blockage of the normal air conduction sound pathways. Conductive hearing loss may be due to ear wax (cerumen) blocking the ear canal or perhaps a foreign object may be lodged in the ear canal. Another example of a conductive hearing loss is when fluid occupies the middle ear space, as might occur with common ear infections (otitis media). In these types of hearing loss medical intervention is required and often the hearing can be returned its normal levels.

Mixed hearing loss, as its name implies, involves both sensorineural and conductive hearing loss components. This type of hearing loss results from problems in both the conductive pathway of the ear as well as hearing loss occurring in the cochlea. This type of loss requires medical intervention to treat the conductive portion of the loss, the remaining sensorineural loss may require treatment through the use of hearing aids.

Degrees of hearing loss

Audiologists use general terms (normal, mild, moderate, severe, and profound) to characterize the degree of hearing loss. Typically it is not a percentage of loss, but rather a category Hearing loss is measured in decibels (dBs) and the general categories refer to an average of the decibel level of hearing loss present.

In general, people with normal hearing (up to 20 dB hearing loss for adults, up to 15 dB for children) can hear most auditory information in normal listening situations. Even some people classified as normal hearing will have difficulty hearing in background noise or extreme listening situations.

Adults with mild hearing loss (between 26 and 40 dB)

May hear reasonably well in one-on-one conversation. These people will miss words or certain speech sounds when speech is quiet or when there is background noise present. Overall they will report only minimal difficulty hearing.

Adults with moderate hearing loss (between 41 and 70 dB)

Miss a lot of speech sounds and telephone conversation. They often ask for clarification of what is being said often times saying “What” in response to portions of conversations. They will have additional difficulties with watching TV at a normal volume level, and tremendous difficulty in hearing in noisy situations. They become increasingly dependent upon visual information and will begin to shy away from social situations.

Adults with severe hearing loss (between 71 and 90 dB)

Need hearing aids to perceive speech sounds almost all of the time. People with severe hearing loss will require increased volume in all listening situations they will have major difficulty listening in the absence of visual information. Use of the telephone will be limited by the need for increased volume. These patients will also find it difficult to hear environmental sounds such as the doorbell ringing or people calling from another room of the house.

Adults with profound hearing loss (91 dB or more)

Cannot hear speech sounds even if they are very loud. These patients require amplification through the use of a hearing aid or cochlear implant for access to auditory information. The use of hearing aids is not for access to spoken language but rather for personal safety and access to environmental sounds like a fire alarm or a car horn. Hearing aids or cochlear implants will not provide normal hearing to these patients but rather an improvement in their hearing which allows them to perceive auditory information.

Implications of Hearing Loss

People with untreated hearing loss (people with hearing loss who do not wear hearing aids) experience a decreased quality of life. Sadness, depression, anxiety, paranoia, and poor social relationships have been showed to result from untreated hearing loss. People with untreated hearing loss may have a difficult time in their personal relationships, their social interactions and their professional lives—often earning thousands of dollars less than their hearing peers. Recent research has shown the longer a hearing loss is left untreated the lower the level of improvement with the use of hearing aids. Similar to any body part with an injury “if you don’t use it you lose it”. Untreated hearing loss overtime prevents patients from ever fully benefiting from what amplification can offer. Studies show most people wait 8 years before remediating a hearing loss from the time of its identification. During this period of time vital listening skills are lost forever.

Common Causes of Hearing Loss

Throughout our lifetimes our ears are exposed to a wide variety of noises such as lawnmowers, telephones, industrial machinery, leaf blowers, chain saws, subways, planes, hair dryers, weapons, and recorded and live music. Many of these sounds occur at loud and potentially hazardous levels. It only requires one truly loud noise to damage your hearing permanently. Continued exposure to loud noise increases the likelihood of developing hearing loss. Although some people are born with hearing loss, most acquire it later in life. Hearing loss can be attributed to a number of causes, these include genetic predisposition (family history), noise exposure (including music, industrial, military and more), diseases of the ear, ototoxic medications (drugs which are toxic to the cochlea) and head trauma to name a few.