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What Is Sensorineural Hearing Loss?
Sensorineural hearing loss (SNHL) is the most common type of hearing loss.
SNHL is caused by damage to your inner ear structures, such as the tiny hair cells in your inner ear or the nerve pathways from the inner ear leading to your brain. SNHL is estimated to account for 9 out of 10 cases of reported hearing loss.
Your inner ear structures, pictured below, include your sensory organ or cochlear and the vestibular nerve and cochlear nerve.
The vestibular nerve is responsible for sustaining body balance and eye movements, and the cochlear nerve is a part of your hearing system connecting the cochlear to the brain.
SNHL is also known as nerve-related hearing loss because it affects the parts of the inner ear that send neural impulses to the brain.
In many cases, sensorineural hearing loss can’t be cured, but it can be treated. Treatment options include drugs, surgery, better management of any underlying conditions, and hearing aids.
Severity SNHL is often categorised on a scale or threshold of hearing loss measured in decibels. Hearing loss on this scale is described as mild, moderate, moderately severe, severe or profound.
There are several different types of SNHL, each with its underlying causes.
5 Causes of Sensorineural Hearing Loss
1. Normal Ageing
Presbycusis is age-related hearing loss caused by the gradual degradation of nerve hair cells in the cochlea. Initially, it reduces your ability to hear higher frequency sounds, but over time, it can make lower frequency sounds unclear, too, making everyone sound like they’re mumbling.
2. Exposure to Loud Noise
Noise-induced hearing loss occurs when excessive noise, usually over a long period, damages the fine hairs in your inner ears that send messages to your brain. People who love listening to loud music may also be damaging their hearing. Noise-induced hearing loss can also happen after a one-off exposure to an intensely loud sound, such as an explosion.
WorkSafe NZ recommends keeping noise levels below 85dB on average and 140dB at peak.
3. Drugs That Are Toxic to Your Hearing
Ototoxic medications or chemicals are substances that injure your cochlea or auditory nerve.
Ototoxic medicines may also affect your vestibular system, which governs your balance and spatial awareness. Some drugs are known to be ototoxic and include some antibiotics, anti-inflammatory medications and cancer chemotherapy drugs.
4. Diseases and Disorders
Hearing loss may result directly or indirectly from an underlying disease or disorder like multiple sclerosis, chronic ear infections, meningitis, measles, mumps and glue ear.
5. Hearing Loss That Runs in the Family
Hereditary hearing loss is a form of hearing loss that runs in families. Your genes might make you more susceptible to hearing loss by contributing to age-related hearing loss, causing some hereditary hearing impairment syndromes, or causing inner-ear mutations that affect your hearing, either at birth or in later life.
Safe Listening: How Loud Is Too Loud?
The amount of noise and the length of time you are exposed to the noise determine its ability to damage your hearing.
Noise levels are measured in decibels (dB). Sounds louder than 80 dB are considered potentially hazardous.
There is growing concern about increasing exposure to loud sounds in recreational settings such as nightclubs, discotheques, pubs, bars, cinemas, concerts, sporting events, and even fitness classes.
The rising popularity of devices such as music players and smartphones often listened to at unsafe volumes and prolonged periods poses a severe threat of irreversible hearing loss.
Use the safe listening chart below as a guide to help you protect your hearing health.
Safe Listening Chart
|Decibels||Example||Safe Listening Time|
|150 dB||Jet take-off (at 25 metres)||0 seconds|
|140 dB||Gunshot||0 seconds|
|130 dB||Jackhammer||<1 second|
|120 dB||Chainsaw||9 seconds|
|110 dB||Live rock music||30 seconds|
|100 dB||Motorcycle||15 minutes|
|90 dB||Petrol lawn mower||2.5 hours|
|80 dB||Sink garbage disposal unit||25 hours|
|70 dB||Home vacuum cleaner||Unlimited|
|60 dB||Typical conversation||Unlimited|