Noise and Hearing Conservation

Developed by Karen Hsi, UCOP EH&S Student Intern

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Hazardous noise exposures occur

On the job…

And off the job…

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Sound Level Meter Instant reading › Quest 2200 › Sound level range from

30 to 140 decibels (dB)

Temporary damage to sensorineural system – temporary threshold shift (TTS)  Permanent threshold shift (PTS) is noise induced hearing loss  Loss of communication  Physiological effects 

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Causes no pain

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Causes no visible trauma

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Leaves no visible scars

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Is unnoticeable in its earliest stages

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Accumulates with each over-exposure

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Takes years to diagnose

Is permanent and 100% preventable

 Continuous

Noise

- 85 decibel, 8 hour time-weighted average (TWA)Action Level ~Hearing conservation programs ~Training ~Annual audiometric examinations

- 90 decibel, 8 hour TWA- Permissible Exposure Level ~Wear Earplugs

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If you must shout to be understood over the background noise when standing about one arm-length away from somebody,

that background noise is potentially hazardous.

Permissible Exposure Limits

Permissible Exposure Limits

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Sound waves cause the eardrum to vibrate Bones in middle ear transmit vibrations to cochlea Receptors (hair cells) in cochlea convert vibrations to electrical energy Brain interprets these electrical impulses as sound

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Nerve cells in the cochlea are tuned to specific frequencies

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Base of the cochlea is sensitive to high frequency sounds

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Tip of the cochlea is sensitive to low frequency sounds

Conductive

Sensory

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Caused by damage to or a malfunction of the outer and middle ear  Some causes › › › ›

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Excessive ear wax Fluid in the ear A torn eardrum Colds

Usually hearing is restored once the cause is diagnosed and treated

Caused by damage to or a malfunction of the inner ear, auditory nerve, or the brain  Causes of sensory hearing loss › Aging, Damage to fetus,

Hereditary, Noise, Disease, Injury, Drugs

Cannot be corrected medically or surgically  Hearing loss in the workplace is typically a sensory hearing loss 

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Imagine you are at a classical concert.. but you are experiencing progressive hearing loss during it. Listen to the difference!

 Indoor (Office Environment) › Office Background Noise–45 to 60 decibels › Elevator-55 to 65 decibels › Normal Conversation-60 to 65 decibels › Copying Machine-65 to 70 decibels  Outdoors (Street) › Street Background Noise– 65 to 75 decibels › Trucks, Buses Driving By-75 to 80 decibels  All

noise levels found are within the Cal/OSHA permissible exposure limits

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Dr. Dean Garstecki, audiologist from Northwestern University, suggests that i-Pod users take precautions Hearing loss found in younger people that is normally found in aging adults › Listening to music at 110 to 120

decibel range

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Earbuds can boost sound signal by 6-9 decibels Follow the 60% volume/60 minute rule

Wear Noise- Cancelling Headphones  Helps to cancel out background noise and prevents listeners from cranking up the volume on their i-pods/mp3 players.  Also recommends use of older style, larger headphones that rest over the ear opening. 

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UC Site Visits › Construction & Shops- Machinery, Backhoe,

Tools, Jackhammers, etc. › Power Plants

Travel – Small Aircraft  Personal Activities/Hobbies 

› Gardening – Lawn Mower, Hedge Trimmer › Carpentry/Tools, Shooting Range, 

Wear earplugs or earmuff to protect your hearing!!

Hearing Loss Due To Noise Exposure Is … Painless Permanent Progressive … and very PREVENTABLE!