Types of Hearing Loss

Types of Hearing Loss | Dr. Ali Ghahary

Hearing loss occurs as a result of your ear and auditory system (which is what processes found information from the ear to the brain) not functioning properly. The auditory system consists of the outer ear, which is made up of the pinna, ear canal and eardrum (also known as the tympanic membrane); the middle ear, which is also made up of the ear drum in addition to the ossicles (three small bones that are responsible for sending the movement of the eardrum to the inner ear); and the inner ear itself, which is made up of the cochlea (the small, snail-shaped organ which is responsible for our hearing), and semicircular canals (which help us with our balance.)

Hearing loss can range from mild to profound. Someone with mild hearing loss may be unable to hear sounds that are softer, while someone with moderate hearing loss may not be able to hear sounds (such as speech) at their normal level. Hearing loss can also be severe and an individual may either only have the ability to hear loud sounds, or not hear any sound at all – which is also often referred to as deafness. Hearing loss can be unilateral (occurring in one ear) or bilateral (occurring in both ears); pre-lingual or post-lingual (before or after someone learned to speak), symmetrical or asymmetrical (the same in both ears, or differs between ears), progressive or sudden (develops slowly over time or happens quickly); fluctuating or stable (has periods where it gets better, or stays the same), or it can be congenital or acquired (either present at birth or it develops later in life.)

When it comes to suffering from hearing loss, it is a condition that is separated into three different categories:

• Sensorineural hearing loss
• Conductive hearing loss
• Mixed hearing loss

Sensorineural hearing loss, which is the most common type of hearing loss, occurs when there is damage to the inner ear or to the auditory nerve, weakening or preventing nerve signals from transferring to the brain – and it is also considered a permanent form of hearing loss. If someone is born with sensorineural hearing loss, it can be caused by a genetic syndrome or be passed from the mother to the fetus inside the womb as a result of different infections like toxoplasmosis, rubella, or herpes; or even be the result of premature birth. However, it typically occurs later in life, and can be caused by varying triggers such as being exposed to loud noises for extended periods of time, different viral infections (such as measles, meningitis or mumps), head trauma, tumours, or medications. It can also be the result of aging. Individuals with sensorineural hearing loss will have trouble with both the loudness and clarity of sounds in which they may either seem too loud or too quiet, may feel as though the speech of others seems slurred, may have ringing in the ears (also known as tinnitus), and you may also feel off-balanced and/or dizzy. As mentioned, sensorineural hearing loss is considered permanent, though some patients may benefit from hearing aids or cochlear implants.

Conductive hearing loss is considered to be a lesser common form of hearing loss in which there is damage or obstruction to the outer or middle ear, preventing sound from travelling to the inner ear. Causes of conductive hearing loss can be anything from a build-up or impaction of wax in the ear, bone-line protrusions that develop in the ear canal resulting in a blockage, otitis externa (more commonly known as swimmer’s ear), injury to or ear infection of the ear drum, rapid changes in air pressure, as well as abnormal growths/tumours within the middle ear. Someone with conductive hearing loss may experience symptoms including pain in one or both of their ears, a sensation of pressure in one or both ears, may have an easier time hearing out of one ear than the other ear, may feel as though their voice either sounds different or louder, may have trouble having telephone conversations, and may even smell a foul odour coming from their ear canal. Individuals with conductive hearing loss may also find that they have an easier time hearing sound from radios or televisions if they simply turn up the volume. The type of treatment one receives for conductive hearing loss depends on the cause. For example, of wax impaction is the cause, then it can be treated by extraction of earwax. If an ear infection is the cause, then the patient would be given a course of antibiotics. In cases that are considered more severe, a patient may need a surgical procedure or require the use of a hearing aid or other implantable device.

Lastly, mixed hearing loss, which is a combination of sensorineural and conductive hearing loss, and is usually caused as a result of the ear sustaining trauma. Symptoms will often be a mix of those associated with both sensorineural and conductive hearing loss, and treatment will also be dependent on those symptoms.