Patrice Johnson

Hearing Protection: the Dangers of Noise Exposure

Outer ear: Ear canal

Middle ear: Ear drum (tympanic membrane)

Ossicles

Inner ear: CochleaSemi-circular canalsAuditory nerve

The Ear

How we hear

Outer ear: Ear canal

Middle ear: Ear drum (tympanic membrane)

Ossicles

Inner ear: CochleaSemi-circular canalsAuditory nerve

The Ear

How we hear

Outer ear: Ear canal

Middle ear: Ear drum (tympanic membrane)

Ossicles

Inner ear: CochleaSemi-circular canalsAuditory nerve

The Ear

How we hear

 

      

             

       

            

Noise

What is noise? Different

sources: Occupational:

Mining Building

industry

Recreational:Personal stereos e.g. Ipods

Power toolsLawn mowersMotor sportsNight clubsConcerts

Risk of damage depends on:

1. Level of noise 2. Time of exposure

(how long and how often)

3. Pitch (frequency) of sounds can also effect the degree of damage. High pitch more damaging.

Noise

How much noise?

Sound at a distance: As the distance is doubled from the sound

source the sound level decreases 6dB SPL As the distance is halved from the sound

source the sound level increases 6dB SPL What does this mean?

Further you are from the noise source, the better

Hearing damage risk is negligible below 75 dB

A vacuum cleaner emits about 85dB

Noise Levels

Exposure Length: For every 3dB louder, the sound is twice as strong so the exposure time should halve.

Safe exposure limit is 85

decibels for eight hours a

day.

100dB = 15min

Cory Portnuff/Dept. of Speech, Language and Hearing Science, University of Colorado; Brian Fligor/Children's Hospital Boston and Harvard Medical School

iPods

Cory Portnuff/Dept. of Speech, Language and Hearing Science, University of Colorado; Brian Fligor/Children's Hospital Boston and Harvard Medical School

iPod listening time vs % volume

Personal stereos

Ipods at low volumes are fine

Ipods at high volumes for long periods of time can damage your hearing

What happens when sounds are too loud? Causes damage to the hair cells in the

cochlea This means softer sounds may no longer

be transmitted

Cochlear Hair Cells

Healthy Damaged

Permanent

Hearing Loss

The effect of repeated noise exposure on hearing is usually permanent.

Hair cells can not repair themselves. There is no cure for this hearing loss.

Temporary

Hearing Loss

Noise can temporarily cause a hearing loss by “tiring out” the hair cells

First signs: ringing in the ears after noise exposure.

Typical hearing loss from noise exposure

Hearing Loss and Noise Exposure

Ability to hear soft and medium high pitch tones eg. birds, mobile ringing, is lost

Missing beginning or end of a word or sentence

Conversations in a group or busy environment e.g. restaurant, meetings

Difficulties to differentiate similar words Musical difficulties: melody and pitch

discrimination

How high frequency hearing loss impacts hearing

Judging harmful noise levels

1. Noise is as loud or louder than heavy traffic

2. You have to raise your voice to speak to someone 1 metre away

3. Things sound different after you’ve been exposed to noise

4. You hear ringing or other noises in your ears after you’ve been exposed to noise

Noise Induced Hearing Loss (NIHL)Can NIHL be detected early? Early signs of temporary hearing loss

Tinnitus Muffled hearing e.g. After a loud concert

Usually goes undetected until it affects the ability to follow conversations in noisy environments e.g. Restaurant

NIHL

Does Noise-Induced Hearing Loss cause Any Pain? Generally no Only very loud sounds such as a bomb result

in pain General loud sounds e.g. lawnmower do not

cause pain, but can result in hearing loss

Impact of Hearing Loss

The Listen Hear! Report (Access Economics February 2006):

Financial cost to Australia of $11.75 billion per annum or 1.4% of GDP

1 in 6 Australians is affected by hearing loss

Expected to increase to 1 in every 4 Australians by 2050

With 36% of hearing loss attributable to excessive noise exposure

Protecting Your Hearing

Avoid loud noises/ music Wear earplugs when exposed to loud

noise/music (eg. Concert and motor races) Loud music can be just as dangerous as

noisy machinery. Balls of cottonwool or paper tissue won’t

protect your hearing. Learn to fit earplugs correctly. Poorly fitted

earplugs offer little protection.

Protecting Your Hearing

Ear Plugs Foam disposable ear plugs Musician’s ear plugs – 3 levels of

attenuation and allow music or voice to be monitored

Noise plugs Ear muffs

Summary

Impact on hearing determined by: How long How loud How often

Avoid loud sounds Use hearing protection

Questions

Any Questions?