Article with contributions from Dr Ho Eu Chin, ENT Specialist at The ENT Clinic (an associate clinic of Hearing Partners)
Noise Induced Hearing Loss (NIHL) is a form of hearing loss caused by constant exposure to loud sounds or a one-time exposure to an extremely loud noise such as an explosion. The damage caused by such sounds is irreversible and permanent, and can affect one or both ears.
The speed that NIHL progresses from mild to severe (where individuals will really struggle to hear) depends on the duration and intensity of the noise exposure.
In 2020, it was the second-highest contributor to occupational diseases in Singapore. In addition, another study found that 1 in 6 youths in Singapore is at risk of developing leisure NIHL from listening to music on their earpiece.
This article will cover the symptoms and causes of NIHL, how it is diagnosed, the symptomatic treatments available and how it can be prevented. We will also share answers to some frequently asked questions about NIHL.
How Loud is Too Loud?
Sounds are measured in decibels (dB). The louder the sound, the higher the decibel level.
The diagram below illustrates some of the common sounds and their average noise levels. It serves as a gauge to understand the kind of sounds considered too loud for our ears (sounds at or below 70dB are generally safe).
Symptoms of Noise Induced Hearing Loss
The symptoms of NIHL are not immediately apparent and may take time to develop. Some of the most common symptoms include:
- Inability to hear high-pitched or soft and faint sounds
- Ringing or buzzing in the ear, also known as tinnitus
- Feeling of pressure or fullness in the ear
- Normal conversations that seem muffled or distorted
Causes of Noise Induced Hearing Loss
NIHL is caused by prolonged exposure to loud noises or a one-time exposure to a thunderous sound such as an explosion.
The sound waves produced by such noises create vibrations that can damage the tiny hair cells in our ears. These cells, also known as stereocilia, do not have the ability to regenerate or regrow. Hence, the damage is irreversible and permanent.
There are various ways in which we can be exposed to loud noises. Below are 2 such common ways:
Workplace exposure
Employees who are susceptible to NIHL include those in metalworking, ship-building, construction and manufacturing industries, to name a few.
Workplace exposure
Employees who are susceptible to NIHL include those in metalworking, ship-building, construction and manufacturing industries, to name a few.
These individuals are likely to be exposed to excessive noise that is above the recommended limit of 85dB per 8-hour work day as stipulated by the Workplace Safety and Health Council (WSHC). The longer they are exposed to such noise levels, the higher the chances of developing NIHL.
Leisure activities
Certain leisure activities that are popular amongst teens and young adults are exposing them to dangerous levels of noise. This includes attending concerts and visiting clubs. Some individuals also enjoy music at excessive volumes through their earphones.
Prolonged exposure to such loud music and sounds can lead to NIHL over time.
These individuals are likely to be exposed to excessive noise that is above the recommended limit of 85dB per 8-hour work day as stipulated by the Workplace Safety and Health Council (WSHC). The longer they are exposed to such noise levels, the higher the chances of developing NIHL.
Leisure activities
Certain leisure activities that are popular amongst teens and young adults are exposing them to dangerous levels of noise. This includes attending concerts and visiting clubs.
Some individuals also enjoy music at excessive volumes through their earphones. Prolonged exposure to such loud music and sounds can lead to NIHL over time.
Diagnosing Noise Induced Hearing Loss
NIHL can only be diagnosed through audiometric testing by a certified hearing care professional. It is a non-invasive and risk-free procedure where you will be put through a series of hearing tests to measure your ability to hear the softest levels of sounds at individual pitches.
Treatment for Noise Induced Hearing Loss
While NIHL cannot be treated medically or surgically, hearing aids and cochlear implants can help you hear and communicate better. These treatments can help you better cope with your condition and improve your quality of life.
Hearing aids
Recommended for: Mild to profound hearing loss
Hearing aids may help to manage symptoms of NIHL by amplifying the surrounding sound waves. This makes sounds louder and clearer for the user.
Even though they are struggling to understand what other people are saying, it is common for people to think they can delay the use of hearing aids because they can still hear some noises. However, you should consider the use of hearing aids once you or people around you notice you have difficulties catching what others are saying.
According to Dr Ho Eu Chin, an ENT (Ear, Nose and Throat) specialist at The ENT Clinic, people without hearing loss are able to easily differentiate between speech and background noise. However, when the background noise becomes too loud, they too might have difficulty comprehending speech.
For people with untreated hearing loss, it is likely that their brains start to forget how to differentiate between speech and background noise, even when it is not that noisy. Hearing aids can, therefore, help re-train the brain to differentiate between the two. Moreover, if you are using technologically advanced devices like Oticon hearing aids, you can hear better with less effort.
Cochlear implants
Recommended for: Severe to complete hearing loss
Cochlear implants are tiny devices with 2 parts – the internal part is surgically inserted under the skin while the external part sits behind the ear. They bypass the damaged portions of the ear to deliver sound signals to the auditory nerve, which is subsequently directed to the brain.
Cochlear implants are only used as a second-line treatment when hearing aids are no longer benefiting the user. Hearing through cochlear implants is quite different from hearing with hearing aids. However, this is still preferred to being in total silence permanently. There is a learning curve and users typically need 3 to 6 months to adapt to cochlear implants.
Prevention for Noise Induced Hearing Loss
According to Dr Ho, it is recommended to avoid exposure to noise levels exceeding 85dB for more than 8 hours a day. He also added that the safe exposure time needs to be halved for every 3dB increase. This means that if we are exposed to noise levels of 88dB, the safe exposure time will decrease to 4 hours.
Here are some ways you can protect your ears and avoid NIHL:
Practice safe listening habits
Since NIHL is caused by exposure to loud noises, adopting safe listening habits can lower your risk of developing this condition. For example, you can limit the duration and intensity of such noises by lowering the volume of your earpiece (below 50% of the maximum), opting for more quiet leisure activities and more.
When it comes to playing music with earphones, Dr Ho recommends getting a headset with both passive and active noise-cancelling or noise-reduction functions. They help to cancel out high and low-frequency competing “background” sounds so users are able to listen to their music at a safer level.
Wear ear plugs or ear muffs
In situations where loud noises are inevitable, do use good quality ear plugs or external ear muffs. They can help to muffle and dull the noise, minimising the noise trauma to your inner ear.
FAQs About Noise Induced Hearing Loss
Who is at risk of noise induced hearing loss?
NIHL can affect anyone regardless of age.
However, those who are constantly exposed to loud noises such as construction workers and landscape technicians are more likely to develop NIHL. Those who listen to loud music on their headphones over prolonged periods of time are also at risk.
How do I know if a sound is considered too loud?
Sounds at or below 70dB are generally safe. Though it is hard to determine the noise level without using the proper apparatus, it is generally considered safer to have the volume below 50% for whichever device you are listening to. Here are some general guidelines signalling that a sound may be too loud:
- You find yourself having to shout to another person even when they are within an arm’s length of you
- Your ears hurt from the sound
- There is ringing or buzzing in your ears after the sound subsides
How long does it take for loud noises to damage my hearing?
It depends. Extreme loud sounds can cause immediate damage to your ears. On the other hand, it may take years of constant exposure to noises above 85dB to progressively damage your hearing.
Which part of the ear is damaged in noise induced hearing loss?
Loud noises primarily affect the cochlear, an organ in the inner ear. When the tiny hair cells in the cochlear become damaged, NIHL occurs. These tiny hair cells do not have the ability to regrow or regenerate, making the condition permanent.
Are there any side effects of noise induced hearing loss?
NIHL can severely impact your quality of life due to the communication difficulties experienced. As your hearing abilities deteriorate, you will not be able to hear high-pitched sounds and may have trouble distinguishing words with “sh”, “s”, “th” and “f”.
NIHL can subsequently lead to social isolation, depression, and dementia. In fact, a new report published by the Lancet Commission suggests that moderate hearing loss can increase one’s risk of dementia by 3-fold.
Is noise induced hearing loss permanent?
Yes, NIHL is permanent as the damage to the hair cells in the cochlea is irreversible. While there are no medical or surgical cures for NIHL, there are symptomatic treatments available such as hearing aids and cochlear implants that can help users regain a better understanding of what they hear.