Noise and Hearing Conservation

UCOP Safety Meeting March 2010

Developed by Karen Hsi, UCOP EH&S Student Intern

Noise and Acoustics

Noise and Acoustics Hazardous noise exposures occur

On the job… And off the job…

Measuring Noise

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

from 30 to 140 decibels (dB)

Effects of Noise

Temporary damage to sensorineural system – temporary threshold shift (TTS)

Permanent threshold shift (PTS) is noise induced hearing loss

Loss of communication Physiological effects

Noise Induced Hearing Loss

Causes no pain Causes no visible trauma Leaves no visible scars Is unnoticeable in its earliest stages Accumulates with each over-exposure Takes years to diagnose

Is permanent and 100% preventable

Noise and Acoustics

Regulatory Levels

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

How do I know if the noise levels are hazardous?

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.

Time Weighted Average

Permissible Exposure Limits

Time Weighted Average

Permissible Exposure Limits

How We Hear…

How the Ear Works…

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

Reponses of the Cochlea

Nerve cells in the cochlea are tuned to specific frequencies

Base of the cochlea is sensitive to high frequency sounds

Tip of the cochlea is sensitive to low frequency sounds

Two Types of Hearing Loss

Conductive Caused by damage to

or a malfunction of the outer and middle ear

Some causes› Excessive ear wax› Fluid in the ear› A torn eardrum› Colds

Usually hearing is restored once the cause is diagnosed and treated

Sensory 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

High-Frequency Sounds of Speech

K P

SH

STH

TF

CH

H

Let’s hear what it sounds like to have progressive hearing loss… Imagine you are at

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

Typical UCOP Noise Levels 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

Noise exposure from MP3 Players and/or i-Pods with headphones 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 Earbuds can boost sound signal by

6-9 decibels Follow the 60% volume/60 minute

rule

Other Options… 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.

Other Types of Noise Exposures

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 …

PainlessPermanentProgressive

… and very PREVENTABLE!