Noise and Hearing Conservation

1. Noise and Hearing Conservation Image credit: OSHA

2. Session Objectives • You will be able to: • Understand the effects of noise on hearing • Identify sources of noise in your workplace • Describe the purpose of audiometric testing and be able to interpret your test results • Select, fit, and use hearing protection

3. What Is Sound? • Sound is a longitudinal pressure wave of energy with the following characteristics: • Frequency (pitch) measured in hertz (Hz) • Pressure (loudness) measured in decibels (dB) • Frequency and pressure of a sound wave with duration of exposure determine the risk of hearing loss

4. Noise Sources • Machinery, tools, and equipment emit sounds of varying loudness and in particular frequencies • Continuous or intermittent • Low-frequency equipment noise sources cause hearing loss in the speech frequencies

5. Sound Pressure Levels ofCommon Noises • Noise Source Loudness • Whisper 10 dB • Conversation 65 dB • Shop tools 90 dB • Pneumatic drill 100 dB • Woodworking shop 110 dB • Abrasive blasting 115 dB • Jackhammer 130 dB

6. OSHA Noise Exposure Limits • 90 dBA TWA for 8-hour exposure • 95 dBA TWA for 4-hour exposure • 100 dBA TWA for 2-hour exposure • 105 dBA TWA for 1-hour exposure • Use engineering controls, administrative controls, and personal protective equipment (hearing protection) to meet standards

7. Indicators of High Noise Levels • Noisy conditions can make normal conversation difficult • 80 dB–People have to speak very loudly • 85-90 dB–People have to shout • 95 dB–People have to move close together to hear each other at all

8. How Is Noise Hazardous? • Noise can result in temporary or permanent hearing loss • It can cause you to misunderstand communication • It can cause you to miss important safety warnings • It can create unhealthy stress

9. How We Hear Sounds • Sound waves enter the ear canal • Eardrum vibrations pass along tiny bones • Tiny hairlike cells flow back and forth • The auditory nerve sends signals to the brain that are registered as sound

10. How Hearing Is Damaged • Hearing ability relies on delicate parts that can be damaged in the inner and middle ear • Hairlike cells in the inner ear are flattened by high noise levels and injured over time • Hearing loss is gradual • Hearing damage is permanent Image Credit: OSHA

11. Hearing Loss • Hearing loss is any reduction in the ability to hear • Two types of loss • Temporary hearing loss (temporary threshold shift) may occur immediately following a high noise exposure • Permanent hearing loss (standard threshold shift)

12. Signs of Hearing Loss • Difficulty hearing people speak • Inability to hear certain high-pitched or soft sounds • Noise or ringing in ears • Getting complaints that the radio or TV volume is too high Image Credit: Tom Ouimet

13. Evaluating the Noise Exposure Hazard • Conduct a noise survey • Identify and characterize high-noise sources • Identify impacted employees • Monitor impacted employees • Repeat monitoring Image Credit: Tom Ouimet

14. Noise Hazards—Any Questions? • Do you understand • The hazards of excessive noise and how to identify them? • Signs and symptoms of hearing loss? • Measuring hearing loss?

15. Elements of the Hearing Conservation Program • All employees exposed to >85 dBA for 8 hours must participate • You receive: • Baseline and annual audiograms • Annual training on hearing loss • Hearing protection is provided • Exposure assessment conducted periodically

16. Audiometric Exams • Exams can detect early signs of hearing loss • Typically measures hearing threshold at six frequencies • Hearing thresholds are compared with previous audiograms

17. Standard Threshold Shift (STS) • Hearing loss has occurred if you have experienced a standard threshold shift (STS) • Hearing ability changed by an average of 10 dB • Revised hearing protection required for STS

18. Baseline Annual Has an STS Occurred? Image Credit: Tom Ouimet

19. An Example of Hearing Loss in Carpenters Image Credit: Tom Ouimet

20. Hearing Protection Use • Voluntary use if exposed to an 8-hour TWA of 85-90 dB • Mandatory use when: • Exposed to an 8-hour TWA of 90 dB • Exposed to an 8-hour TWA of 85 dB and have suffered an STS (hearing loss) or have not had a baseline hearing test

21. Hearing Protection Devices Noise Reduction • Hearing protection devices must reduce employee noise exposure below an 8-hour TWA of 90 dB • Employees with STS, noise exposure reduced below an 8-hour TWA of 85 dB • Noise reduction ratio (NRR) • Earplugs: use 1/3 of NRR • Earmuffs: use 1/2 of NRR

22. Hearing Protection Devices— Earplugs and Canal Caps • Must be properly inserted to seal the ear canal • Slowly roll and compress foam into cylinder • Insert into ear canal while compressed • Keeps noise from reaching the eardrum • Cotton is not an earplug Image Credit: State of WA-WISHA Services

23. Hearing Protection Devices—Earmuffs • Sealed against head with ears fully enclosed • Hair out from muffs • Glasses and caps do not interfere with seal • Headband adjusted so cushions exert even pressure • Cleaned with warm, soapy water and rinsed

24. Any Questions? • Do you understand • Audiometric testing? • Our hearing protection program? • When to use hearing protection? • Hearing protection devices?

25. Key Things to Remember • Hearing is a very important sense—don’t lose it • Noise exposure of 85 dB or more can cause hearing loss • Hearing loss cannot be cured or repaired • Hearing tests are conducted annually and can detect hearing loss • Hearing protection devices must be worn in high-noise areas