NOISE AND ACOUSTICS ~ Hierarchy of Controls Noise + Acoustics Ototoxic Chemical Exposures • Confirmed Ototoxics • Ethyl Benzene • Lead and Inorganic Compounds (Pb) • Styrene • Toluene • Trichloroethylene • Possible • Carbon disulfide • n-Hexane • Xylene Ototoxic Chemicals Noise Hearing Loss
How We Hear • The Auditory System Chem/Elec Acoustical Hydraulic Mechanical
Hearing Protection Selection Hearing Protection Devices (HPDs) Single-Use / Multiple-Use / Detectable Earplugs Banded Earplugs Intelligent Hearing Protection Sound Amplification Earmuffs Passive Earmuffs Radio & Stereo Earmuffs
Hearing Protection Selection Uniform / Flat Attenuation HPDs
Hearing Protection Selection Frequency in Hz 1000 2000 8000 4000 250 500 125 63 50 45 40 35 Attenuation in dB 30 25 20 15 Uniform Attenuation Earplug 10 Conventional Earplug 5 0 Uniform / Flat Attenuation HPDs Variation in attenuation is only 5 dB in speech range (250 - 4kHz) Speech will sound more natural with this earplug.
Hearing Protection Selection Intelligent Hearing Protection
Hearing Protection Selection Hazards of Overprotection Choosing a protector with an NRR higher than necessary may result in overprotection • Verbal communication may be hindered • Warning alarms may not be heard • Machine noises may be too diminished • HPDs may be removed
Hearing Protection Selection Hazards of Overprotection Insufficient Protection 85 dB Acceptable Protection 80 dB Optimal Protection 75 dB Acceptable Protection 70 dB Possible Overprotection
Hearing Protection Selection Hazards of Overprotection In the United States, 76% of noise-exposed workers need no more than 10dBof protection. 90% need no more than 15dB of protection.
Hearing Protection Selection • 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 Hearing Protection Selection Factors Comfort
Hearing Protection Selection • 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. Hearing Protection Selection Factors Noise Reduction
Hearing Protection Selection • 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 Hearing Protection Selection Factors Size
Hearing Protection Selection • Keep workers connected to their environment • Uniform attenuation allows speech/signals to be hear more naturally • Sound amplification earmuffs for workers with hearing impairment Hearing Protection Selection Factors Communication
Hearing Protection Selection • Consider job requirements in HPD selection • Detectable earplugs for process industries • Hi-visibility earmuffs for dark/high traffic areas • Dielectric HPDs for electrical environments Hearing Protection Selection Factors Job Requirements
Hearing Protection Selection • 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 • Roll vs. No-Roll earplugs • Foam vs. multiple-use earplugs • Clean and replace ear cushions on earmuffs every 4-6 months • Clean and examine multi-use earplugs daily Hearing Protection Selection Factors Hygiene
Hearing Protection Selection • Cap-mounted earmuffs for hard hats • Multiple-position earmuffs for full-brim hard hats • Ultraslim neckband earmuffs with welding shields • Respirators preventing communication • Eyewear interfering w/seal of earmuffs, attenuation Hearing Protection Selection Factors Use w/ Other PPE
Hearing Protection Selection • Awareness of surroundings • Understand what is happening around you • Communicate with co-workers (face-to-face or 2-way radios) • Increased personal safety, avoid other risks • Avoid isolation from environment Hearing Protection Selection Factors Connect w/ Environment
Noise Reduction Rating • How much noise is reaching the ear of the worker ? It’s completely UNKNOWN!
Noise Reduction Rating • Noise Reduction Rating • A laboratory estimate of the amount of attenuation achievable by 98% of users when properly fit • A population-based rating ― some users will get more attenuation, some will get less The NRR is only a population estimate, not a predictor of individual attenuation.
Noise Reduction Rating • 10 human subjects tested in a simulated industrial room • Tested with ears open / occluded at nine frequencies • Each subject tested 3x • NRR calculated to be population average Determining the NRR A test subject in the Howard Leight Acoustical Lab, San Diego, CA, accredited by the National Voluntary Laboratory Accreditation Program (NVLAP)
NRR Noise Reduction Rating NRR 26 28 30 32 24 22 14 18 20 19 23 25 27 Determining the NRR 5 4 3 Number of test subjects 2 1 Attenuation
Noise Reduction Rating • De-Rating Methods (US/CAN) Reduce NRR Earmuffs NRR – 25% Formable Earplugs NRR – 50% All Other Earplugs NRR – 70% NRR ÷ 2 pending feasibility of engineering controls Class System A up to 100 B up to 95 C up to 90 Fit Test
Noise Reduction Rating Real-World Attenuation≠ NRR Real user attenuation <0 to 38 dB 50 40 30 20 Attenuation in dB 10 Retraining and refitting resulted in an average +14 0 -10 192 Users of a Flanged Multiple-Use Earplug (NRR 27)
Noise Reduction Rating Three New Labels
Noise Reduction Rating Determining New NRR • 20 human subjects tested in a simulated industrial room • Subject trained then fits their own earplugs • Tested with ears open / occluded at 9 frequencies • Each subject tested 2x • NRR calculated to be population average
New NRR (NRsa) Noise Reduction Rating 80% achieved > 20 dB 20% achieved > 26 dB 5 4 3 Number of test subjects 2 1 24 22 11 14 18 20 26 28 30 33 19 23 25 27 Attenuation
Noise Reduction Rating How to Apply the New Label Two-number range displays the estimated protection achievable by minimally-trained users [80%] versus proficient users [20%]. A wider range indicates greater variability in the fit of that HPD. Smaller ranges indicate more consistency of fit. For example, earmuffs will usually have a tighter fitting range than earplugs, and may have a smaller NRR range. 80% 20%
Noise Reduction Rating NRR Change Resources PDF and other articles available at www.hearforever.org
Noise Reduction Rating 30 min 5 min 10 min 15 min Biggest Factors in Achieving PAR 1.FIT 2. WEAR TIME 30dB A worker who selects an earplug with an PAR of 30 but then removes that HPD for just … effectively reduced his 8-hour PAR to just … 22 dB 18 dB 26 dB 24 dB In noise exposures, small intervals of no protection quickly void large intervals of adequate protection.
Noise Reduction Rating • For extreme noise environments • To estimate the protected noise level, add about 5 dB to the higher NRR protector Dual Protection EARMUFF EARPLUG + = DUAL PROTECTION
Noise Reduction Rating What Can I Do Now? Although the new labeling regulation takes effect whenever the final rule is published by the EPA, there are a number of actions you can take now to prepare your Hearing Conservation Program for the change. • Evaluate Noise Spectra • Determine if spectral balance corrections will be necessary • One-on-One Training • Research studies confirm that one-on-one training is superior to group training
Noise Reduction Rating What Can I Do Now? • Evaluate HPD Selection • Determine whether they are appropriate for your noise environment. • Use the Howard Leight Hearing Protector Selector for recommendations. • Update Training Program • Hold “Toolbox Training” with fit training refresher
Noise Reduction Rating What Can I Do Now? • Use Earplug Fit Testing • Train how to properly fit HPDs • Select appropriate HPDs • Document adequate protection • Use In-Ear Dosimetry • Measure, document noise dose employee is exposed to during work shift
Next Generation of Hearing Conservation Technology New Measurement Technologies Personal Sound Exposure Monitoring (PSEM) Earplug Fit Testing
Next Generation of Hearing Conservation Technology Earplug Fit Testing Provides an accurate,real-world picture of your employees’ hearing protector effectiveness. • ID if your employees are • Getting the right protection • Need additional training • Need different earplug • Problem Solver: • Eliminate De-Rating Schemes • Improve One-on-One Training • Validate Hearing Protector Selection • Adapt to Impending NRR Change
Next Generation of Hearing Conservation Technology Fit Testing Systems Real Ear at Above Threshold (REAAT) Loudness Balance Commercial Available System
Next Generation of Hearing Conservation Technology Personal Measurement Systems Personal Sound Exposure Monitoring (PSEM) Commercial Available Systems
Next Generation of Hearing Conservation Technology Fit Testing as Best Practice OSHA / NIOSH / NHCA Alliance Research studies have suggested that when individuals are involved in the fitting process and receive positive feedback on the proper fit of their earplug, they will be more likely to have a positive attitude about protecting their hearing and will be more apt to use hearing protection correctly and consistently in the workplace. This positive outcome should result in reducing noise-induced hearing loss in the workplace. Available for download at www.hearingconservation.org
Next Generation of Hearing Conservation Technology Fit Testing Comments from Workers "I know how to better fit my earplugs now.” "Learned A LOT about best earplugs for me." "I found a more comfortable fit. It was very beneficial." "Recently had a threshold shift. Found better earplugs." "I was amazed with the results after being shown the proper way to use earplugs. "Very glad I did the fitting test. Now I know the correct way to fit my ear plugs.” "I had no idea I was not using my earplugs correctly." "Feel like am protected now!"
Next Generation of Hearing Conservation Technology PROs & CONs of Fit Testing
Hearing Protector Fitting 0 dB 0 dB >33 dB EAR #1 EAR #2 EAR #3 How much protection?
Hearing Protector Fitting Frequency in Hz 1000 2000 3150 4000 6300 8000 250 500 125 90 Max Good Fit NRR = 33dB Max Poor Fit NRR = 0dB 80 70 60 Attenuation in dB 50 40 30 20 10 0 -10 Good Fit vs Bad Fit
Hearing Protector Fitting 1. Rollentire earplug into a crease-free cylinder 2. Pull Backpinna by reaching over head with free hand, gently pull top of ear up and out 3. Insertearplug well into ear canal and hold until it fully expands Roll-Down Foam Earplugs
Training + Motivation Personalize Hearing Loss • Show, Don’t Tell • Provide copy of annual audiogram to worker • Use personal examples to demonstrate consequences of hearing loss • Ask questions: • What is your favorite sound? • What sound would you miss the most if you couldn’t hear? • What sounds connect you to people and your environment?
Training + Motivation Demonstrate Future Risk • Training Materials • www.hearforever.org • www.hearingconservation.org • www.grc.nasa.gov/www/acoustics • www.cdc.gov/niosh/topics/noise • www.dangerousdecibels.org www.hearforever.org/ AIH
Training + Motivation www.hearforever.org
Training + Motivation • Send Clear Message On + Off Job • HC Part of Everyday Life • Include recreational hearing conservation in annual training • Provide extra HPDs for home use • Promote Hearing Conservation at company/family events
Training + Motivation Remove Barriers to HPD Use • Make HPDs Available • Highlight “where to find HPDs” in annual training • Make sure HPDs are well-stocked and accessible • Include group of workers in selection process for increased acceptance • Offer wide variety to match comfort, job requirements
Training + Motivation Checking Off the OSHA Amendment List Health effects of noise Purpose of hearing protection Advantages/ disadvantages of various Selection, fit, use and care of HPD Purpose and procedures of audiometric testing