By Prof. Asha Yathiraj,  Professor of Audiology and Monica Rathna Mala, Audiologist Gr. I, JSS Institute of Speech & Hearing

International Noise Awareness Day is observed every year on the last Wednesday of April to raise awareness about the hazardous effects of noise on hearing, health and overall quality of life.

This year, the 27th Annual International Noise Awareness Day is celebrated today (April 27, 2022).  An easy way to prevent hearing loss is to know what causes it, so that timely action can be taken to avoid the problem. One of the most common cause of acquired permanent hearing loss is exposure to loud noise. It is possible to prevent hearing loss and maintain healthy hearing by following certain precautionary measures. This article provides information regarding noise-induced hearing loss and how it can be prevented. 

The intensity of noise, which is measured in dB SPL, can cause a hearing loss depending on the duration of exposure to noise. In general, sounds above 85dB SPL are harmful, depending on how long and how often the person is exposed to them. Louder noise levels can initially lead to a temporary hearing loss. With repeated exposure to noise, it can become permanent. Permanent hearing loss cannot be reversed either through medication or surgery. Hearing loss due to ageing is accelerated by exposure to loud noise.

The most common types of noise that may result in a noise-induced hearing loss are machinery noise at industrial set-ups, construction sites, as well as constant traffic noise, especially in airports and train stations. Individuals working in these areas are at risk of developing noise-induced hearing loss.

However, recent trend in excess use of personal music systems at loud levels by younger generation can also produce a hearing loss. Loud music in concerts can result in a hearing loss in the musicians as well as the audience. Sudden loud impulse noise can result in a hearing loss even if it is for a short duration.

What are the effects of noise exposure on hearing?

Noise exposure initially leads to difficulty in hearing high frequency sounds. The person may not be able to understand speech although it may be audible. This is especially the case when trying to listen when multiple people are speaking at once. Other symptoms include ringing/ buzzing sounds in the ear (tinnitus), tendency to speak loudly, sleep disturbances and even balance problems.

How to prevent noise-induced hearing loss?

The general rule of thumb is to stay away from sounds that are too loud/ too near/ too long in duration. Exposure to very loud sounds should be avoided even if it is for a short duration (example: loud crackers). Those exposed to noise as part of their occupation should use ear protective devices like ear plugs and ear muffs. Music should be enjoyed by listening to it at a low-to-medium volume, with breaks in between. Regular hearing check-ups by an audiologist is recommended to detect hearing loss at the earliest.

Types of noises, their intensity and the maximum allowable duration of exposure

Type of noise	Decibel (dB SPL) level	Average decibel (dB SPL) level	Maximum duration of exposure allowed
Industrial/ machinery noise	90 – 120 dB	105 dB	up to 1 hour per day*
Loud music	100 – 120 dB	110 dB	up to 30 mins per day*
Construction noise	90 – 110 dB	100 dB	up to 2 hours per day*
Heavy traffic	80 – 90 dB	85 dB	up to 8 hours per day*
Aircraft noise (Take off/ landing)	90 – 110 dB	100 dB	up to 2 hours per day*

[* As per OSHA, 1974]