Noise Induced Hearing Loss

Written by: Kelsey Spurrell, Clinical Audiologist

We all know that working in a loud environment can impact your hearing. However few people actually understand the impacts of noise induced hearing loss.

Hearing loss can be caused naturally with age but this doesn’t ordinarily happen until later in life. If you are experiencing hearing loss earlier and have been exposed to loud sounds, it is more than likely noise induced. NIHL (noise induced hearing loss) is caused by two factors working together: the INTENSITY of the noise and the LENGTH OF TIME a person is exposed to it. Repeated exposure in combination with these two factors gradually produces NIHL a form of SNHL (sensorineural hearing loss). SNHL is permanent and this is due to the death of hair cells within the inner ear.

NIHL normally presents itself as a high frequency hearing loss. This means that high pitched sounds, such as the /t/, /k/, /s/ sounds in speech, become more difficult to hear. This results in the perception of muffled speech. Other common symptoms of NIHL are tinnitus (ringing in the ears), the inability to understand speech, and difficulty following conversations when there is background noise. It’s important to know that NIHL can progress over time, and can eventually impact low pitched sounds, such as vowel sounds in speech.

But what is noise? Noise is any loud unwanted sounds. In fact, anything that is 85 dBA or more is considered dangerously loud. For instance, a lawn mower, motorcycle, jackhammer, and even a blow dryer can all produce sounds that can cause hearing loss.

The cause of NIHL may be most often work related, but the effects are felt far beyond the workplace. According to a 2000 Board of Health Report to the City of Toronto: there is evidence indicating that noise can effect general health, which include but are not limited to an increased risk for cardiovascular disease, chronic fatigue, and damages to mental health such as anger and anxiety. The report also states that “more people are affected by noise exposure than any other environmental stressor.”

While there are a variety of negative side effects associated with NIHL, it is somewhat preventable. It`s your duty and your right to protect yourself from any dangers in the workplace.

HOW TO PROTECT YOUR HEARING FROM NOISE

1) WEAR HEARING PROTECTION

2) TURN DOWN THE VOLUME

3) LIMIT EXPOSURE TIME TO LOUD NOISE

4) MONITOR YOUR HEARING PROFILE

Noise level exposure is regulated by both federal and provincial legislatures. Occupational exposure limits for noise can be described as the maximum duration of exposure based on different levels of noise. Two important factors for calculating this are the criterion level and the exchange rate. The criterion level is defined as the level of noise permitted for an 8 hour work shift. In N.B., regulations state the criterion level to be 85 dBA, that’s the level of a power drill. The exchange rate states that when the noise levels increase, exposure to the noise must decrease. In N.B., regulations define the exchange rate to be 3 dBA. So for every 3 dBA increase in noise level, the exposure time must be reduced by half. This means if the noise level at your workplace increased to 88 dBA then you should only be exposed for 4 hours!!

To protect your hearing, try to stay away from the source of the loud noise but most importantly use hearing protective devices. A variety of these exist including foam ear plugs, custom ear plugs and ear muffs.

The following infographic provides a great loudness scale for reference: