Types of hearing loss
In general, hearing loss mentions three important aspects: type of hearing loss, degree of intensity of hearing loss, and configuration of hearing loss. The degree of intensity of a person’s hearing loss is classified by the severity of the problem. One of the most common classification systems are:
|Degree of hearing loss||Hearing ability (dBHL)|
|Normal||Soft sounds can be heard, commonly above 20dBHL|
|Mild hearing loss||It is difficult to understand speech and have good communication in noisy environments.
At best between 25 and 39 dBHL
|Moderate hearing loss||Speech is hard to understand without the aid of a hearing aid.
At best between 40 and 69 dBHL.
|Severe hearing loss||A hearing aid or implant is required. In the best case between 70 and 89 dBHL|
|Deep hearing loss||When this occurs, the person has to resort to lip reading and / or sign language, or an implant.
At best over 90 dBHL
Three basic types of hearing loss can be identified.
- Conductive hearing loss: occurs when there is an impediment in the path of sensory waves, which means, when sound does not travel easily through the outer ear canal to the eardrum and the ossicles of the middle ear. With conductive hearing loss, sounds are muffled and less easy to hear. However, this type of hearing loss can be corrected by medical or surgical intervention. Some possible causes are considered such as:
- Fluid in the middle ear due to colds or allergies.
- Ear infections (otitis media).
- Malfunction of the Eustachian tube.
- Perforation in the eardrum.
- Excess wax in the ear.
- Swimmer’s ear (external otitis).
- Object lodged in the ear canal.
- Malformation of the outer ear, ear canal, or middle ear.
Some symptoms are considered to be able to identify this condition: speech tends to sound intelligible, but when the volume is high enough and there is not too much background noise. Conventional hearing aids help, but sometimes it is not enough.
- Sensorineural hearing loss: This is due to the existence of some damage to the inner ear (cochlea) or to the nerve conduits between the inner ear and the brain. This sensorineural hearing loss reduces the ability to hear faint sounds, even when speaking at sufficient volume, it may not sound clear or sound muffled. Most of the time, due to its severity, sensorineural hearing loss cannot be repaired by medical or surgical intervention, and that is why it is considered the most common type of permanent hearing loss.
Some possible causes are:
- Toxic Hearing Medications.
- Hearing loss in the family (genetic or hereditary).
- Head injuries
- Malformation of the inner ear.
- Exposure to very loud noises.
To more easily identify this hearing loss, some symptoms are considered: the first being if it is suffered in both ears, it is difficult to understand speech, even when it sounds loud enough, instead if it is suffered in only one ear , you may have trouble locating where sounds are coming from or hearing with background noise.
- Mixed hearing loss: It is a combination of conductive hearing loss and sensorineural hearing loss, which implies that there is damage to both the outer or middle ear and the inner ear. It occurs when conductive hearing loss changes simultaneously with sensorineural hearing loss. In other words, there may be damage to the outer or middle ear, as well as the inner ear (cochlea) or the auditory nerve.
The symptoms to be able to identify this condition are: if the hearing loss is mostly conductive, speech tends to sound intelligible, but only when the volume is high enough and the background noise is not crossed. otherwise, if the hearing loss is predominantly sensorineural, it may be difficult to understand speech, even when it appears to be loud enough.
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