NIHL or Noise Induced Hearing Loss is the expression used by Audiologist and Health and Safety specialists to describe hearing loss caused by very loud sounds or large sound doses.

What is a very loud sound?

These are often called impulse sounds and, in terms of sound pressure level, start at around 135dB. They usually don’t last very long and are common in military and heavy industrial situations. They are so damaging to your hearing that there are strict Health and Safety Regulations about your exposure to them when you are at work.

What is a large sound dose?

These are the result of exposure to sound over a period of time and come in many forms. For example, this could be the sound of machinery in a factory or from attending live music or sports events, but more worryingly from wearing headphones.

How is the dose calculated?

Your sound dose is a complex combination of three variables: how loud you listen, how long you listen for and the energy content of what you listen to. It is normally calculated in a laboratory and makes it impossible for you to calculate your own sound dose. Learn more about safe decibel levels to avoid hearing loss.

What is the most common cause of large sound doses?

Historically, large sound doses would probably have been caused by your occupation but the Health and Safety Regulations now make this unlikely. Live music and sport provide significant doses, but we generally attend them infrequently so they have less long-lasting impact on your hearing. For most of us, the biggest cause is from using headphones to listen to music or for gaming, something which many of us do for long periods every day. Read more about the various causes of hearing loss.

How do I know if I am or have been subject to a large sound dose?

If you have ever had “dull” hearing after attending a noisy gig or nightclub, you have had Threshold Shift, caused by the hair cells in your inner ear becoming tired by the noise. This is an indication of an “excessive” noise dose. You generally will not know if you have been subjected to a merely “large” dose. The effect of exposure is cumulative over a lifetime so you may not know until it is far too late. The hearing damage caused in this way is permanent.

What can I do to protect myself?

If you work in a noisy environment your employer is legally obliged to supply you with suitable hearing protection and you are similarly required to use it as instructed.

If you wear headphones for work, ask your employer to provide you with headphones which are either limited or, if they are for personal use, fitted with an HDM® Pro U personal dosimeter. Interestingly, even if you wear your own headphones to listen to music at work (e.g. to decrease distractions in an open plan office) your employer is still liable for any hearing damage incurred.

At live music or sporting events, the recommendations are that you wear earplugs, especially before the main act or event.

If you wear headphones to listen to music on your smartphone, you should consider downloading the HearAngel® hearing protection app.

Learn more about the different ways to prevent hearing loss.