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Noise Induced hearing loss - Understanding the Hazards

By Adam Shelverton
Senior Rehabilitation Consultant

What is Noise Induced hearing loss -NIHL? Most sounds, which we refer to as noise, are in everyday life at safe decibel levels which do not cause injury. However, noise can be harmful when it is too loud, even for a brief time, or when it is both loud and prolonged.


Given the cause of hearing loss is noise which anyone can be affected by, how can it be prevented.

NIHL can be:

  • Immediate (Immediate traumatic exposure) or take a long time to develop
  • Can be temporary or permanent
  • Can effect one or both ears

What causes NIHL?

  • Hearing loss can be caused by a single loud noise such as an explosion, or as more commonly seen in employers liability claims, by continuous exposure to loud noise over an extended period of time eg working in a noisy factory. Recreational activities also can put you at risk of NIHL eg. attending loud concerts, listening to music at high volume through headsets etc.
  • Noise is measured in units called decibels.
  • Noise of less than 75 decibels is unlikely to cause hearing loss even after a long period of exposure.
  • Noise at or above 85 decibels can cause hearing loss if exposure is long or repeated.
  • The louder the noise, the shorter amount of time it takes for hearing loss to occur.
  • We can experience physical pain at sound greater than 125 decibels.

How does noise damage our hearing?

Sound waves enter our ear and travel through the ear canal to the ear drum. The ear drum vibrates from the incoming sound waves and sends these vibrations to 3 tiny bones in the middle ear. These bones turn the sound vibrations in the air into fluid vibrations in a structure called the cochlea. Fluid vibrations in the cochlea cause tiny microscopic hair known as Stereocillia to move. These hair movements cause a chemical reaction which creates an electrical signal. It this  electrical signal that is carried to the brain by the auditory nerve where it is interpreted into sound that we recognise.

Most NIHL is caused by the damage and eventual death of these microscopic hair cells inside the ear. Human hair cells cannot regenerate so if they sustain damage, they are damaged they are damaged permanently.

Some average decibel ratings of some familiar sounds

Rustling leaves: 20dB

Normal conversation: 60dB

Jet engine (100feet): 140dB

12 Gauge Shotgun Blast: 165dB

Loudest sound possible: 194dB

NIHL can be prevented.

  • NIHL is the only types of hearing loss that is completely preventable. If individuals and employers understand the hazards of noise, steps can be taken to prevent permanent damage.
  • Identify which noises can cause damage (those at or above 85 decibels)
  • Wear hearing protection when involved in a noisy activity/working environment (some ear protection may need to be bespoke depending on the nature of the task/activity)
  • If you can’t reduce the noise or protect yourself against it then move away from it
  • If friends and colleagues are not using hearing protection when they should be – alert them to the hazards of noise.
  • Protect the ears of young children who are too young to understand how to protect their own.
  • If you think you might have hearing loss – have your hearing tested as soon as possible.

NIHL Claims – are on the increase

There are numerous theories why claims are increasing:

  • These claims are often long-tail and involve exposure over  many years or even decades.
  • The impact of the Employers Liability Tracing Office (ELTO) means that it is now much easier for claimant solicitors to identify historical insurers. Previously, it had been difficult for claimant solicitors to identify historical insurers either because they are no longer trading or simply could not be identified.

Your contact

Your contact

Adam Shelverton

Adam Shelverton

Rehabilitation Manager

Tel: +44 (113) 2906321