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Part of auditory wellness, which includes the health of your hearing, is to know what can be damaging to your hearing and what your limits are. Damage is insidious because we can’t always feel or tell when our hearing is being harmed.

Workplace noise or a noisy environment (like traffic noise) can cause hearing impairment, tinnitus, hypertension, heart disease, annoyance, sleep disturbance, changes in your immune system and birth defects. A study by the World Health Organization attributes 50,000 deaths per year within the EU to illness brought on by exposure to traffic noise.

In addition to these health problems elevated noise creates stress increases accident rates, and can stimulate aggression.

sound from a loudspeakerThe louder the noise – the greater the damage.

Loudness is the intensity of the sound, and is related to the amplitude of the sound wave.

Because sound is a form of energy, loud sounds can cause hearing damage, and because the damage is cumulative over time, our hearing tends to deteriorate over time.

What we refer to as loudness is more accurately known as the Sound Pressure Level which is measured in decibels (dB). Sound is a form of energy, and the decibel scale reflects that. The scale is a logarithmic scale – an increase of 3 dB represents a doubling of the sound pressure level.

In Canada, Occupational health and safety has recognized the impact of sound in the workplace, and has placed limits on maximum exposure to prevent damage.

A worker may work safely in an environment for 8 hours a day with a noise level of 85 db, although most factories require hearing protection if the noise level exceeds 80 dB to provide an extra level of safety. That same worker can only remain in an area with a noise level of 90 dB for 2 hours per day, 100 dB for 15 minutes and 110 dB for 1 minute before damage might occur.

And here’s the root of the problem. Our ears are imperfect instruments for detecting the loudness of sound. While an increase of 3dB represents a doubling of the intensity of the sound, our ears perceive a 10dB increase as a doubling of the loudness of the sound. So the sound is actually much louder, and much more damaging than we perceive.

To put all this in perspective, here are some everyday examples and their decibel levels:

0 dB Threshold of hearing
10 dB pin drops

20 dB

whisper at 1 meter

40 dB

quiet conversation

60 dB

normal conversation

85 dB

beginning of hearing damage

90 dB

subway train

104 dB

beginning of pain at some frequencies

110 dB

rock concert

125-130

Typical DJ system

130 dB

jet engine

140 dB

all frequencies are painful

147 dB

formula 7 racing car

150 dB

rock concert “The Who”

145-165

dB fireworks

165-180 dB

typical thunder

 

By definition, zero dB is the threshold of human hearing. An increase of 3 dB indicates a doubling of the intensity – of the energy of the sound. Normal conversation is usually measured at 60 dB, 63 dB represents a conversation that is twice as loud, 66 dB is twice as loud again, and so on.

Most people feel pain with sound levels between 110 and 130 dB.

Damage to your hearing does not heal. It is considered permanent. I encourage you to become aware of the sounds around you and how they may be affecting you.

For a quick test of your hearing, visit the University of New South Wales, Hearing Test at www.phys.unsw.edu.au/jw/hearing.html. This is not intended to be a definitive test, but it is a very good indicator of your current hearing.

 

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