1. Samar El-Sayed

2. Sound is Vibrational Energy Travels in Waves from a Source FREQUENCYINTENSITY Cycles per Second Hertz (Hz) loudness of the sound Decibels (dB)

3. How We Hear Sound waves enter the ear canal striking the eardrum. When eardrum vibrates, ossicles conducts vibrations to the cochlea. Tiny hairlike cells in cochlea respond to vibrations by generating nerve impulses. Brain interprets nerve impulses as sound. Acoustical Mechanical Hydraulic Chem/Elec

4. What is Noise? Unwanted or undesired sound. Sound that has potential to cause hearing impairment. An intense sound capable of damaging the inner ear

5. Effects of Noise Auditory Acute acoustic trauma Sudden, permanent SNHL caused by single exposure to an intense Impulse sound, 130-140dB Noise-induced hearing loss Extra – auditory Interfere with communication Physiological effects Annoyance

6. Auditory effects of Noise Temporary threshold shift (TTS) Temporary loss of hearing shortly after exposure to noise. Resolves over a period of hours or days Permanent threshold shift (PTS) Permanent hearing loss due to damage of sensory cells.

7. Nerve cells in the cochlea are tuned to specific frequencies Base of the cochlea is sensitive to high frequency sounds (red dots) Tip of the cochlea is sensitive to low frequency sounds (green dots) Hearing and Frequencies

8. Safe Noise Levels At safe noise levels, sound waves move along the cochlea without damaging receptor cells Low noise Normal cochlea

9. Loud Noise Levels High noise levels damage the first turn of the cochlea – where high frequency sounds are heard…and lost High noise Damaged cochlea

11. Causes no pain Causes no visible trauma Leaves no visible scars Is unnoticeable in its earliest stages Takes years to notice a change Is Permanent + 100% Preventable Noise-Induced Hearing Loss

12. Indicators of NIHL Time-linked to noise exposure High-frequency hearing loss Usually bilateral (both ears) Gradual progression over time mostly irreversible Appropriate symptoms (tinnitus, muffled hearing)

13. Noise + Acoustics Hearing Conservation Program Action Level – 85 dB Hearing Conservation Program implemented Hearing protectors made available Annual audiometric testing & training 85 dB TWA 90 95 Permissible Exposure Limit – 90 dB  Hearing protectors required

14. Elements of Hearing Conservation Program Noise control measures Engineering Administrative Hearing Protectors Workers education Noise Monitoring Periodic audiometric evaluation

15. Hierarchy of Controls ADMINISTRATIVE CONTROLS Rotate Workers Extended Breaks 2 nd /3 rd Shift ENGINEERING CONTROLS Vibration Pads Enclosures Barriers Isolation PERSONAL PROTECTIVE EQUIPMENT

16. Time Weighted Average Permissible Exposure Limits

17. Time Weighted Average Permissible Exposure Limits

18. Hearing Protection Selection Earplugs Advantages Comfortable for extended use Free head movements Good for tight work spaces Worn with hats, eye protection, respirators Disadvantages Must be replaced periodically Small and can easily be lost Hygiene issues in dirty environments

19. Hearing Protection Selection Bands Advantages Very convenient for intermittent noise Readily available around neck when not in use Disadvantages Lower attenuation than most earplugs Some noise transmission through band

20. Hearing Protection Selection Earmuffs Advantages Easy to get proper fit Good for intermittent noise Advantages Can feel hot/heavy with extended wear Compatibility with other PPE

21. Comfort Noise ReductionSizeCommunicationJob Requirements Hygiene Use with Other PPE Hearing Protection Selection Factors The right hearing protector should feel comfortable One protector may not satisfy all workers Offer a variety of earplugs or earmuffs to meet varying worker needs and preferences Selecting HPDs with suitable attenuation for noise environment Avoid overprotection in marginal noise environments Consider banded earplugs for intermittent noise or electronic earmuffs for impact noise. Every ear canal has its own shape and size Ensure proper fit with variety of earplug sizes and shapes Sized multiple-use earplugs Low-pressure foam earplugs for smaller ear canals Keep workers connected to their environment Uniform attenuation allows speech/signals to be hear more naturally Sound amplification earmuffs for workers with hearing impairment Consider job requirements in HPD selection Detectable earplugs for process industries Hi-visibility earmuffs for dark/high traffic areas Dielectric HPDs for electrical environments Proper care and maintenance can extend life and performance of HPDs Examine and clean all multiple-use earplugs daily Clean and replace ear cushions on earmuffs every 4-6 months Select HPDs that can work with other PPE without compromise Cap-mounted earmuffs for hard hats Multiple-position earmuffs for full-brim hard hats Ultraslim neckband earmuffs with welding shields

22. How much protection? 0 dB 33 dB EAR #1 EAR #2 EAR #3

23. Workers education Effects of noise on hearing Purpose of hearing protectors Advantages and disadvantages of different types of hearing protectors Attenuation of different types of hearing protectors Instructions on selection, fitting, use, and care of hearing protectors Purpose of audiometric testing

24. Noise Measurement Devices SOUND LEVEL METER Sound is measured immediately in a specific area PERSONAL DOSIMETER Sound “averaged” throughout day for sample employee/job

25. Pure tone audiometry Basic test to find out if a hearing loss is present or not. During the test the test person wears a headphone or insert ear phones through which pure tones at different frequencies are being presented. level at which tones are barely audible is found, is the hearing threshold levels

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32. Speech audiometry A speech reception threshold (SRT) Two-syllable words like "hotdog," baseball," and "cupcake" are presented at various intensity levels and the worker repeats them or point to a picture. SRT is determined by the lowest level of sound intensity needed for the patient to correctly identify 50% of these words.

33. Speech audiometry Speech discrimination test Evaluates the patient's ability to comprehend a list of single-syllable words presented at a comfortable listening level. The percentage of words the worker is able to correctly repeat or identify is then recorded.