This topic provides information about sensorineural hearing loss (SNHL). Be sure to check our general page on all types of hearing loss if you are looking for more information.
In a poetic way, the five senses are your brain’s portal into the world. Without sight, hearing, taste, touch, and smell, your brain would simply exist in an empty state of introspective consciousness.
As ubiquitous as these senses are, they’re complicated enough that not a lot of people understand them – and as with any complicated system, there is a lot that can go wrong. In fact, there are so many recognized hearing loss problems that they are split into two main classifications – conductive and sensorineural.
If we consider the process of sound entering your ear to be a road trip, conductive problems happen in the first half – from the outer ear to the middle ear. You can read about these in our article on conductive hearing loss.
Sensorineural hearing loss, meanwhile, is any problem that occurs during the second half of the journey – between your inner ear and your brain. Sensorineural hearing loss is the more serious of the two, as it’s generally irreversible, and will most likely need a hearing aid to treat.
If you want to know what goes down in the first half of the hearing process – the sound entering the ear – check out our article on conductive hearing loss. Once the three tiny bones within the ear have done their part, the sensorineural aspect of hearing begins.
These tiny bones stimulate the cochlea, which is full of fluid and microscopic hair cells. The movement of the fluid pushes these hairs around, and they send signals – via neurons – to the brain's auditory cortex (the section dedicated to understanding sound.)
Sensorineural hearing loss occurs when something goes wrong during this chain of events. This article will go over the major ways that sensorineural hearing loss can occur, and look at ways it can be prevented.
Sensorineural loss can be split into two subcategories. These are fittingly referred to as “sensory” and “neural” hearing loss.
Sensory hearing loss causes
Sensory hearing loss refers to any hearing loss sustained in the cochlea, which is the organ that contains those tiny hair cells. Most forms of sensory hearing loss occur due to damage or death of these hair cells. Let’s look at some of the bigger causes.
Presbycusis is the scientific name for your hearing slowly degrading over time. This affects every single one of us, and is the reason that people stop being able to hear higher frequencies as we age.
This phenomenon is the reason that young people are more susceptible to high-frequency sounds. This is why some businesses employ “The Mosquito,” an alarm that emits a high-frequency noise to deter teens from loitering outside of stores. This sound was then craftily re-engineered into a ringtone, meaning that if a student’s phone went off in class, the teacher was unable to hear it.
Hearing ability will always degrade over time. It’s irreversible, and it’s also not something to be ashamed of. People experience it at different rates, but it does slowly happen to all of us.
• Loud noise
The most obvious cause of all, sensorineural hearing loss can be caused by extended exposure to loud noise. The threshold for hearing damage is generally accepted to be around 80 dB, which means any time you’re exposed to sound above that level, you’re doing damage to your ears. For reference, 80dB is around the volume of a ringing phone or buzzing alarm clock.
Don’t worry, that’s not as bad as it sounds – when we say “extended exposure,” we really mean extended. For example, the Occupational Safety and Health Administration (OSHA) demands that companies have a hearing conservation program if employees are exposed to 85 dB over an 8-hour workday.
If you have a job or hobby that entails frequent noise exposure, proper hearing protection is crucial. Take periodic breaks or wear hearing protection to minimize damage, and always be aware of loud machinery or environments.
• Internal damage
It’s possible that sensorineural damage can come from inside the head. High fevers and certain chemicals can create conditions which are unsuitable for the cochlea, and the hair cells within.
For example, nicotine, alcohol, and certain medications can poison or suffocate the hair cells. This is known as “ototoxicity” – when something is toxic to your ear. Similarly, a disease that brings a high fever can essentially fry these cells to death.
It can be tricky avoiding either ototoxicity or fevers. Sometimes a crucial medication can be ototoxic, while a feverish disease can be unavoidable. All the advice we can give is to try and live a conventionally healthy lifestyle, with a good diet, plenty of exercise, and as little drinking and smoking as possible.
Sensory hearing loss encompasses every cause we’ve listed so far. While there are many forms of neural hearing loss, they can all be covered within the same section. Neural hearing loss affects the final step of the hearing process: the brain.
This classification includes dysfunction of the cranial nerve, which connects the cochlea to the auditory centers of the brain, as well as any damage to the auditory centers themselves. Sadly, like other nerve damage (such as damage to the spinal cord) thibe in s is completely untreatable, and the only solution is to find methods of living with it.
The good news is, if you don’t already have neural hearing loss, it’s very difficult to get. Short of an incredibly unlucky instance of brain damage, most sufferers of neural hearing loss are born with their condition.
So what are the sensorineural hearing loss treatment options? The answer, you’ll find, is almost exclusively going to be hearing aids. Since repairing or reviving the interior hair cells is impossible with today’s technology, the only treatment you can receive is one that aids and maintains your remaining cells.
Most of the causes we’ve listed so far have been gradual, and therefore perhaps unnoticeable. However, sometimes someone can undergo what is known as “sudden sensorineural hearing loss.”
As the name would imply, this can happen over the course of just a couple of days. This is one of the bigger mysteries of the hearing healthcare world – while there are a lot of theories as to the causes of sudden sensorineural hearing loss (SSHL), like physical trauma, autoimmune disease, or ototoxic influence, the exact cause (or causes) have yet to be determined.
However, the treatment for SSHL is a completely different story to that of regular sensorineural hearing loss. It can sort itself out within a week or two, but this is a bit of a gamble, as it can just as likely become permanent. The safer bet is to go and see a hearing specialist as soon as possible.
The sooner it is treated once detected, the greater the chance of recovery. For this reason, sudden sensorineural hearing loss is considered a medical emergency, and treatment should be prescribed by an otolaryngologist or otologist as soon as possible.
The main difference between these two kinds of hearing loss is the question of what causes them. While both will lead to muffled or impaired hearing, as well as similar side effects (including fatigue, reclusion, or balance issues), the categorization exists to help classify the reasons behind the hearing loss.
Imagine your hearing is represented by a wind-up toy robot. Sensorineural hearing loss is as if the robot has an internal issue, like a damaged wire or a missing gear. Conductive hearing loss would be more of a mechanical issue, as if the robot were missing a leg or in need of a greased joint.
As you might be able to tell from this comparison, conductive hearing loss is a bit easier to address than sensorineural hearing loss. A cleaning or repair will return your ear/robot to peak efficiency. With a sensorineural issue, however, the internal issue will be a lot harder to address – likely requiring a hearing aid or a cochlear implant.
In the end
If you feel like you’re undergoing significant hearing loss, you should go and see a hearing professional, who’ll be able to diagnose your condition and show you the proper next steps.
If you’re considering an appointment, our online tool can book you a free consultation with your nearest hearing healthcare professional.