NOISE INDUCED HEARING LOSS- HOW LOUD IS TOO LOUD?

NOISE INDUCED HEARING LOSS

Have you ever experienced ringing sensation in ears or sudden loss of hearing ability after a brief exposure to loud sound like a blast, gunfire or after attending a concert?

Headphones

Hearing loss caused by exposure to loud noise resulting in damage to hearing cells is known as noise induced hearing loss. When exposure to loud noise happens at the workplace as in a factory it is known as occupational hearing loss. Hearing loss can occur due to unsafe recreational noise exposure as when using headphones at high volume.

Acoustic trauma-  Hearing loss occurs due to exposure to a brief, very loud sound as in blast, gunfire. Because of the abrupt nature of hearing loss, patients usually report immediately. It can be associated with severe earache and rupture of eardrum occasionally.

Noise induced hearing loss- Hearing loss occurs due to continuous exposure to  loud noise over a long period of time. It is gradual in onset and the patient might not notice it or ignore the signs of hearing loss to report only when his daily activities are affected.

Hearing loss has a profound impact on quality of life. The patient is not able to enjoy his daily activities, conversations and social gatherings. It is strongly associated with low self esteem and depression. 

                  “Blindness cuts us off from things,

                        But deafness cuts us off from people”

                                                            - Helen Keller.

Hearing loss due to loud noise exposure is usually associated with tinnitus. Tinnitus is ringing, hissing, roaring or clicking type sounds perceived by the patient. These sounds are more disturbing in quiet surroundings and at night time. Tinnitus can also cause sleep disturbances and disturbance to concentration thus reducing learning and work efficiency.

How loud is too loud? 

A sound’s loudness is measured in decibels (dB).To get an idea of how loud this is, whisper is about 30 dB, normal conversation about 60 dB, traffic noise is 80 dB and  maximum volume in personal musical devices amounts to 110 dB.

Safe permissible limit is 85 db for 8 hours a day, 5 days a week. 

But, it should be remembered that for  every 5 dB increase in sound above the safe limit, the permissible time limit gets reduced by half.

What are the factors that determine the risk of noise induced hearing loss?

Important factors determining hearing loss are noise intensity, duration of exposure and nature of exposure. Higher the intensity of sound above the safe permissible limit, more is the risk of noise induced hearing loss. Exposure to loud noise can be either continuous or intermittent in nature, continuous exposure has a higher risk of causing noise induced hearing loss.

Another concern of the youth is the use of headphones, be it for recreational purposes or for the purpose of conversation. Are you practicing sound " hearing hygiene"? We usually raise our voice when speaking in a noisy environment so that we are audible. Similarly, we tend to turn up the volume high of headphones to overcome the surrounding noise or the ambient noise.

What all precautions to be taken when using headphones?

Listening to loud music through earphones and headphones can increase the risk of noise induced hearing loss. While using headphones, the volume should be just enough so that you can enjoy your music comfortably. It is advisable to use noise cancelling headphones as this can reduce the risk of injury as you don't have to raise the volume to overcome surrounding noise. Some devices have settings where you can limit the volume by default.

Follow the rule of 60/60, your volume shouldn't be more than 60 percentage of device volume and limit the duration of using headphones to 60 minutes at a stretch.

When to suspect hearing loss?

Do you have any difficulty with understanding speech in noisy environments?

Have any friends or family members noticed a problem with your hearing?

Do you have to frequently ask people to repeat sentences?

Do you need to turn up the television or music volume?

If you have any of the above issues or a muffled hearing, you need to test your hearing. Early detection is important as it helps to stop disease progress and you can be started on rehabilitation at the earliest.

Screening for hearing impairment

Noise induced hearing loss affects the hearing function at higher frequencies initially,so the  patient usually  doesn't notice it as the normal speech frequency (500 to 2000 Hz) is not affected. This emphasizes the importance of screening people who are at risk. So by proper screening methods, noise induced hearing loss can be picked up early and rehabilitated accordingly.

It has also been observed that there is early onset of normal ageing of the auditory system, this could be due to the damage of cells that helps in hearing caused by increased noise pollution in recent years. Honking noise is more problematic as it continues for hours during rush hours in traffic signals and cities.Two wheeler honking can go up to 85 dB. This needs to be addressed by strict regulation and by restricting the noise level of horns.

Below is a viral video of an experiment done by Mumbai police to check noise pollution at traffic signal.

 

"HONK MORE, WAIT MORE !"

What are the precautions to be taken at the workplace?

Do you have to raise your voice to speak to someone at one arm length, then noise is likely at hazardous level at your workplace. It should be remembered that noise is different from other occupational exposures because noise exposure even happens outside the workplace. You can check the noise level at your workplace by using a sound level meter. Noise sources that cannot be made quieter, need to be insulated or else restricted. It is advisable to use ear protectors like ear muffs or ear plugs when the noise level at work place is above 85 dB. Good quality ear protectors can reduce the noise level by about 35 db. Taking breaks from noisy activity and surroundings can reduce the risk of noise induced hearing loss. Seek medical attention immediately if you feel pain or ringing in your ears.

Sound hearing hygiene includes moving away or avoiding loud noise, reducing the noise to safe permissible levels and using ear protectors. It should be highlighted that even though noise induced hearing loss is permanent and not fully treatable, it is preventable if picked up early stages.