Noise: Best in moderation!

May 15, 2008 by Martin Fortin

Noise: Best in moderation!

We often discuss the legacy that we would like to leave for future generations. This is commendable. Let’s discuss our auditory environment.

Noise is a public health concern. We’re not all equal with regards to this aggressor; certain people are more vulnerable than others. For some, negative effects may be observed after only one significant exposure (tinnitus, hyperacousis), whereas several years of exposure may be necessary for another.

Did you know that noise, in addition to its effects on hearing, can lead to arterial hypertension, cardiac deficits, sleeping and concentration problems as well as an increase of stress hormone levels in the blood stream?

Calling it a disaster seems exaggerated? Nevertheless, all stages of life are affected by noise, starting with the foetus which could be afflicted with hearing loss if the mother is exposed. In some daycares, excessive noise levels are measured (sometimes up to 90 dB). In elementary school, certain noisy conditions can disturb learning, particularly since the auditory system is still immature. Also, some physical education teachers are developing hearing loss due to excessive noise levels in gymnasiums.

For teenagers, trends such as IPods and MP3 players with inserted earphones are becoming an important threat to hearing, as are regular visits where noise levels can potentially by damaging such as in bars, raves and shows.

In adulthood, in addition to the large number of workers exposed to industrial noise, urban noise can also affect the quality of sleep obtained. Add to that some noisy hobbies on week-ends which can limit the possibility of getting an adequate acoustic rest, as well as the noise of various vehicles (bus, cars, snowmobiles, four-wheelers, etc.) and negative effects on our quality of life are likely to be felt.

Noise induced hearing loss is essentially dependent on the amount of noise received. This amount is sometimes called the ‘dose’ and is determined by the intensity (or volume in dB) and its duration.

Over 75-80 dB, sounds can potentially cause an auditory fatigue:

  • Sounds may appear hushed;
  • People must speak louder for us to understand them correctly;
  • A sensation of blocked ear and/or a buzzing/humming in the ears are also possible.

Auditory fatigue is the stage which precedes permanent hearing loss. It’s a hint that your ears need a break from the noise!

Sounds of 105 dB (ex.: portable music player at the maximum volume) can lead to an auditory fatigue after only a few minutes! The auditory resting period should be twice as long as the time of exposure.

In general, when one must scream to be heard, the noise level isn’t safe for our hearing. Collectively, we must be more aware.

As individuals, we also have a lot of power. The purchase of noisy vehicles or the duration of its use is an individual decision. It is up to us to purchase quieter tools and electric appliances! Even our career choice is something we have power over, as is the case for the use of hearing protection. The number of hours spent listening to music and the volume chosen are also individual choices (it’s strongly suggested to keep the volume lower than 6/10th of the way).

Being responsible about your hearing means favouring quieter hobbies, staying away from loudspeakers and raising awareness concerning the damaging effects of noise.

Intensity and human reaction scale (acoustic events and their impact at a one meter distance)

  • Jet plane nearby (140 dB A) : ear pain, irreversible trauma
  • Shotgun (130 dB A) : possible ear pain, risk of ear trauma
  • Ambulance sirens, clubs/bars (120 dB A): vibrations felt throughout the body
  • Power saw, jackhammer (110 dB A): risk for hearing loss if exposed more than 1 min/day
  • Chainsaw, motorcycle, snowmobile, portable music player at its maximum volume (100-105 dB A): risk for hearing loss if exposed more than 15 min/day
  • Metro, lawnmower, watercraft (90 dB A): Stressful and disruptive
  • Numerous factories, diesel trucks, urban traffic, vacuum cleaner (80-85 dB A): Makes communicating and learning difficult, risk for hearing loss if exposed more than 8 hours/day
  • Dishwasher, hair dryer (70 dB A): disruptive, makes telephone conversations difficult
  • Normal conversation (55-60 dB A): Comfortable for communication
  • Quiet office, air-conditioner (50 dB A): Comfortable
  • Quiet conversation (30 dB A): Very soft
  • A watches tic-tac, whisper (20 dB A): Barely noticeable
  • Normal breathing (10 dB A): Barely audible
  • Hearing threshold, no sound (0 dB A)
This chart is taken from the following website: www.ooaq.qc.ca, an Ordre des orthophonistes et audiologistes du Québec memoir, presented during the public consultation concerning off-road vehicles in June 2005.