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39 Cards in this Set
- Front
- Back
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What is Noise?
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What is Noise?
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What is Sound?
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What is SOUND?
May be described in three ways: 1. Amplitude (perceived loudness) = dB 2. Frequency (perceived as pitch) = Hz 3. Time pattern-continuous vs. impulsive |
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Physics of Sound
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Physics of Sound
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Amplitude
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Amplitude
SPL - sound pressure level measurements in (uPa) not practical in scale due to large dynamic range of human ear (0 - 140dB) or (20-200,000,00 uPa) which varies by frequency. dB (Log Scale) - developed to standardize & simplify noise and hearing measurements |
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Frequency Weighting
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Frequency Weighting
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Adding Decibels - example question
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What if we have two noise sources
next to each other. One source is 70 dB and the other is rated 70 dB also. What is the total output for the sources? |
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Adding Decibels
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Adding Decibels
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Adding dB (Approximate)
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Adding dB (Approximate)
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Human Hearing
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Human Hearing
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Hearing Level
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Hearing Level
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Hearing Loss
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Hearing Loss
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Common Audiometric Patterns
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Common Audiometric Patterns
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OCCUPATIONAL HEARING LOSS
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OCCUPATIONAL
HEARING LOSS Defined as partial or complete hearing loss in one or both ears as the result of one’s employment. Includes acoustic traumatic injury as well as noise-induced hearing loss. |
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OCCUPATIONAL HEARING LOSS
Acoustic trauma - |
Acoustic trauma - possible damage to conductive elements (tympanic membrane, ossicles) and/or Cochlear injury
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OCCUPATIONAL HEARING LOSS
Continuous noise (NIHL) |
Continuous noise (NIHL) - sensorineural hearing loss - high frequency hearing loss
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OCCUPATIONAL HEARING LOSS = OSHA
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OSHA requires employers to monitor noise exposure levels in a manner that will identify employees who are exposed to noise at or above 85 (dB) averaged over 8 working hours.
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THRESHOLD SHIFT
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THRESHOLD SHIFT
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Occupational Noise Standard
29 CFR 1910.95 Hearing Conservation Amendment – 1983 |
Occupational Noise Standard, 29 CFR
1910.95 |
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Occupational Noise Standard
29 CFR 1910.95 Permissible Exposure Limit |
Occupational Noise Standard, 29 CFR
1910.95 |
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Occupational Noise Standard
29 CFR 1910.95 “Monitoring.” |
“Monitoring.”
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Sound Measurement
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Sound Measurement
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Dosimeters
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Dosimeters
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Standards
Exposure Limits: |
Standards
Exposure Limits: OSHA : 90 dBA; ACGIH, NIOSH : 85 dBA Action Level: 85 and 80 Exchange Rates: 5 db and 3 db - exchange of noise for time that can be spent there |
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Exchange Rates
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Time OSHA ACGIH, NIOSH
8hr 90 85 4hr 95 88 2hr 100 91 1hr 105 94 0.5hr 110 97 |
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Noise Dose
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Noise Dose
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Hearing Protection
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(i) "Hearing protectors."
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Types Hearing Protection
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GENERAL TYPES OF HPDs
Ear plug: seal against inner walls of ear canal • formable (foam, fiberglass) • pre-molded • custom molded Semi-aural: seal or cap entrance to ear canal; mounted on a head band Ear muff: cup seals against side of head; mounted on a headband or attached to hard hat. |
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Comparison of Hearing
Protection |
Ear Plugs
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Ear Plugs
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Ear Plugs
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Ear Muffs
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Ear Muffs
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Ear Muffs
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Ear Muffs
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Noise Reduction Ratings
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Noise Reduction Ratings
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Methods for estimating the adequacy of hearing
protector attenuation - 1910.95 App B |
(A) Obtain the employee's A-weighted TWA.
(B) Subtract 7 dB from the NRR, and subtract the remainder from the A-weighted TWA to obtain the estimated A-weighted TWA under the ear protector. |
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Record Keeping
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Record Keeping
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Prevention of Occupational
Hearing Loss Control Measures |
Engineering
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Prevention of Occupational
Hearing Loss |
Engineering Controls
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Prevention of Occupational
Hearing Loss |
Administrative
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Noise Control Examples
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Noise Control Examples
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Prevention of Occupational
Hearing Loss |
Personal Protective Equipment
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