Noise-induced Hearing Loss and Prevention

A US National Health and Nutrition Survey revealed that noise is the number one cause of impaired hearing. CDC/NCHS, 2002

Noise damage is one of the leading causes of hearing loss today. Noise-Induced Hearing Loss (NIHL) can occur after a single exposure to a very loud sound, such as an explosion or, more commonly, as the cumulative result of long-term overexposure to moderate or loud sounds, including industrial machinery and music. NIHL is cumulative, permanent and irreversible.


How Noise-Induced Hearing Loss Occurs

NIHL occurs when hair cells lining the cochlea are damaged by sudden blasts of noise or exposure to loud noise over a long time. For instance, close proximity to an explosion, industrial workplace noise or having the volume turned up too high for too long may cause damage to the hair cells in the cochlea.

Prolonged exposure to sounds greater than 85dB can cause hearing threshold shifts that can lead to permanent hearing loss. For every increase of 3dB greater than 85dB, the allowable ‘safe’ listening period is cut in half.  As a guideline, the following are considered within the ‘safe zone’:

  • 2 hours at 91dB
  • 1 hour at 94dB
  • ½ hour at 97dB

Warning signs of noise exposure:

  • Ringing or buzzing in ears
  • Sounds seem ‘muffled’
  • Difficulty understanding speech
  • Difficulty following conversations when there Is background noise

Noise can cause other health issues, beyond hearing damage. According to a 2000 Board of Health Report to the City of Toronto: “Evidence indicates that noise causes indirect health effects, which include but are not limited to an ‘increased risk for cardiovascular disease, negative effects on mood, sleep, performance, reading and memory acquisition’.” The report also states that “more people are affected by noise exposure than any other environmental stressor.”


Prevention of Noise-Induced Hearing Loss

Although NIHL is permanent, it is preventable. Adopting the following safe listening habits can protect hearing from long-term harm:

  • Turn down the volume on MP3 players, TV, car radios, etc.
  • Wear earplugs when loud noise is present at dance clubs, sporting events, noisy workplaces etc.
  • Increase the distance from the sources of loud noise
  • Reduce time spend in noisy environments