HearForever: Best Practices in Hearing Conservation

HearForever: Best Practices in Hearing Conservation

Hearing Protection Selection Noise Reduction Rating (NRR)
Agenda Noise + Acoustics How We Hear Hearing Protection Selection Noise Reduction Rating (NRR) Reducing Costs + Claims for Hearing Loss Hearing Protectors + Fitting Tips Training + Motivation

Noise + Acoustics

Hazardous noise exposures occur
Noise + Acoustics Hazardous noise exposures occur On the Job Off the Job Noise damage can occur on-the-job as well as off-the-job (loud music, shooting, power tools, crowd noise). Good hearing conservation should be practiced, no matter what the setting.

Noise-Induced Hearing Loss
Noise + Acoustics Noise-Induced Hearing Loss Causes no pain Causes no visible trauma Leaves no visible scars Is unnoticeable in its earliest stages Accumulates with each overexposure Takes years to notice a change Noise damage is different from most other occupational injuries. It causes no pain or visible trauma (the ears do not bleed when hearing is being damaged), it leaves no visible scars, it is unnoticeable in its earliest stages (workers with noise-induced hearing loss often do not even notice themselves that they are losing hearing until it is too late), it accumulates with each over-exposure, and it generally takes years to diagnose. (<Space> to add bottom line message) But Noise-Induced Hearing Loss (NIHL) is permanent and 100% preventable. Is Permanent + 100% Preventable

Noise + Acoustics Noise-induced hearing loss is the most common permanent and preventable occupational injury in the world. The extent of the problem is shown in this statistic: The World Health Organization reported a few years ago that noise-induced hearing loss is the most common permanent and preventable occupational injury in the world. World Health Organization

Worker’s Compensation
Noise + Acoustics Worker’s Compensation In many countries, excessive noise is the biggest compensable occupational hazard. Cost of NIHL to developed countries ranges from 0.2 to 2% of its GDP. NIHL is on the rise globally. (Source: WHO) In many countries, excessive noise is the biggest compensable occupational hazard. Cost of NIHL to developed countries ranges from 0.2 to 2% of its GDP. NIHL is on the rise globally. (Source: WHO)

United States Statistics
Noise + Acoustics United States Statistics Most common occupational injury in the United States. 22 million US workers are exposed to hazardous noise at work on a daily basis. Approx. 8 million Americans suffer from NIHL. (Source: NIOSH, 2009) Most common occupational injury in the United States. 30 million US workers are exposed to hazardous noise at work on a daily basis. Approx. 10 million Americans suffer from NIHL. (Source: NIOSH)

Noise + Acoustics Non-Occupational Occupational
Typical noise levels on-the-job and off-the-job … a lawnmower at 94 dB, heavy equipment at 100 dB a rock concert at 120 dB. Unprotected exposures at these levels can cause damage. According to OSHA regulations, no exposures of any duration are allowed over 115 dB.

If you must SHOUT to be understood over background noise…
Noise + Acoustics If you must SHOUT to be understood over background noise… …when standing one arm-length away from another person, that background noise is HAZARDOUS. Here is a good rule of thumb to use in determining whether background noise is 85 dB or higher: If you must shout to be understood by somebody about one arm-length away, that background noise is hazardous.

Noise + Acoustics Do jets, stereos, my neighbor’s dog, air conditioner or mobile phones cause NIHL? To damage hearing, noise must be of sufficient intensity and duration Annoyance noises generally do not have the same intensity or duration to cause damage To damage hearing, noise must be of sufficient intensity and duration. Annoyance noises like air conditioning units or office equipment generally do not have the intensity or duration to cause damage. Every day, we are exposed to loud noises over 85 dB (such as a car door closing), but because these exposures are short duration, hearing is not damaged. The U.S. standards define a hazardous noise level as exposures over 90 dB averaged over an 8-hour workday.

92 The decibel (dB) scale is a logarithmic scale, not a linear scale
Noise + Acoustics The decibel (dB) scale is a logarithmic scale, not a linear scale 92 Represent enormous increases in noise level and risk 83 If the noise source is doubled The noise level only goes up 3 dB 86 The decibel scale is a logarithmic scale, not a linear scale. Similar to the Richter earthquake rating scale, small numbers represent enormous changes. Sound energy that is twice the level of 83 dB is not 166 dB, rather 86 dB. 89 Small increases in decibel level

Permissible Exposure Limits
Noise + Acoustics Time Weighted Average Exposure limits in noise exposure are a trade-off between sound level (measured in decibels) and duration of exposure (time). For an 8-hour exposure, for example, the maximum permissible sound level is 90 dB. Anything beyond 8 hours at this noise level is not allowed. Permissible Exposure Limits

Noise + Acoustics Time Weighted Average 4 But for greater exposure levels, such as 95 dB, the maximum allowed exposure time is only 4 hours. In a time-weighted average (TWA), greater noise levels require shorter exposure times, and lower noise levels allow longer exposure times. 95 Permissible Exposure Limits

Noise + Acoustics Time Weighted Average 87 For a 12-hour workshift, the maximum allowable exposure is only 87 dB. 12 Permissible Exposure Limits

Regulations in the United States
Noise + Acoustics Regulations in the United States OSHA 29 CFR Industry 29 CFR Construction MSHA 30 CFR Part 62 Mining FRA 49 CFR 227/229 Railroads Permissible Exposure Limits 90 dB Action Level 85 dB 80 dB Noise Monitoring Required Not Required Audiometric Testing Annual Every 3 Years Training Required New Hires/Annual Hearing Protectors PEL Dual 105 dB TWA Recordkeeping Required OSHA 300 Log This slide provides an overview of key components in occupational noise exposure standards for general industry, construction, mining and railroads.

Hearing Conservation Program
Noise + Acoustics Hearing Conservation Program Action Level – 85 dB Hearing Conservation Program implemented Hearing protectors made available Annual audiometric testing & training Permissible Exposure Limit – 90 dB Hearing protectors required (<Space> to show a comparison of OSHA’s noise limits.) 85 dB TWA is OSHA’s Action Level, at which hearing protectors must be made available, and a Hearing Conservation Program implemented. 90 dB TWA is OSHA’s Permissible Exposure Limit, at which hearing protectors are required and engineering/administrative controls of the noise must be considered. 90 85 95 dB TWA

Overprotection/Underprotection
Noise + Acoustics Overprotection/Underprotection 20-25% workers exposed between dB will still get NIHL. While HPD use is mandatory at 90 dB, you should protect to at least 85 dB. 20-25% workers exposed between dB will still get NIHL. While HPD use is mandatory at 90 dB, you should protect to at least 85 dB. Avoid overprotection – protected levels below dB can create additional safety risk. Avoid overprotection – protected levels below dB can create additional safety risk.

Noise Measurement Devices
Noise + Acoustics Noise Measurement Devices There are two commonly used methods of monitoring noise levels – area sampling (with a sound level meter) or personal sampling (with a noise dosimeter, also called a sound exposure meter). The sound level meter tells us the instantaneous noise level in a specific area, and is accurate only when noise levels are fairly constant in the area. For mobile workers or fluctuating noise exposures, the noise dosimeter gives a more accurate measure of the unprotected exposure. Using this method, the dosimeter is placed on the belt or pocket of the worker to be monitored, and the microphone is clipped on the collar near the ear. The meter remains on the worker for a certain sampling period – several hours, or even the entire workday – and continuously monitors the incoming noise. At the end of the sampling period, a readout shows the average noise level (or equivalent noise level, Leq) for that entire sampling period. Both of these methods measure the unprotected exposure and then an estimate must be made for the protected exposure. The newest method to measure exposure is to directly measure the individual’s protected exposure with “in-ear dosimetry.” Integrated into earplugs or earmuffs, QuietDose’s in-ear dosimetry measures and records the worker's actual noise dose, with and without protection, over their entire work shift. QuietDose provides real-time monitoring throughout the workday, and alerts the worker when noise dose approaches or exceeds safe limits. When deployed, QuietDose provides the only metric with a direct potential to measure and prevent noise-induced hearing loss from on-the-job exposures, empowering both worker and safety manager to make intelligent decisions about Hearing Conservation. SOUND LEVEL METER Sound is measured immediately in a specific area PERSONAL DOSIMETER Sound “averaged” throughout day for sample employee/job IN-EAR DOSIMETER Collects personal noise dose – the only real measure of risk

NOISE AND ACOUSTICS ~ Hierarchy of Controls
Noise + Acoustics Hierarchy of Controls ENGINEERING CONTROLS Buy Quiet Vibration Pads Enclosures Barriers Isolation ADMINISTRATIVE CONTROLS Rotate Workers Extended Breaks 2nd/3rd Shift PERSONAL PROTECTIVE EQUIPMENT For hazardous noise exposures, the hierarchy of controls should be … 1) Engineering Controls 2) Administrative Controls 3) Hearing Protection

A, B and C Weighing Curves
NOISE AND ACOUSTICS ~ Hierarchy of Controls Noise + Acoustics A, B and C Weighing Curves Most noise measurements in industry are taken using the A-weighting scale. The A-scale is simply a filter applied to microphones in noise measurement devices that replicates the response of the human ear. The human ear is not a perfect microphone – hearing sensitivity in the low frequencies and high-frequencies actually drops off. To account for this drop-off in the low and high frequencies, manufacturers of noise measurement devices include the A-weighting filter so that measurements are similar to what the human ear would hear. (see Best Practices > Articles)

Synergistic Ototoxics
NOISE AND ACOUSTICS ~ Hierarchy of Controls Noise + Acoustics Ototoxic Chemicals Ototoxic by themselves Synergistic effect with noise Large differences in sensitivity Recommend: increased frequency of audiometric testing Confirmed Ototoxics Ethyl Benzene Lead and inorganic compounds (as Pb) Styrene Toluene Trichloroethylene Possible Carbon disulfide n-Hexane Xylene Synergistic Ototoxics Carbon Monoxide Hydrogen Cyanide NOISE Over the decades, a number of chemical exposures have been indentified that also impair hearing. In some cases, the chemical exposure alone can cause hearing loss; in other cases, there is a synergistic effect between noise and chemicals increasing a worker’s sensitivity to noise damage.

How We Hear

The Auditory System How We Hear Chem/Elec Acoustical Hydraulic
Sound waves enter the ear canal and cause the eardrum to vibrate. Bones behind the eardrum transmit these vibrations to the cochlea – the snail-shaped organ where the nerves of hearing are located. Receptor cells in the cochlea convert these vibrations into electrical impulses, and send them to the brain, where we interpret these impulses as sound. When noise damages hearing, it does not damage the eardrum or bones (unless it is a loud blast or explosion). Generally, loud noise damages the receptor cells in the cochlea, and these nerve cells are irreplaceable – they do not grow back like a fingernail. Mechanical

Hearing + Frequencies How We Hear
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) The base of the cochlea is sensitive to high frequency sounds -- it is this part of the cochlea that is damaged when loud noise enters the ear. It makes little difference whether the incoming sound is high-frequency or low-frequency – ANY loud noise will cause a high-frequency hearing loss, because the region of the cochlea hit hardest by incoming sound waves is the region where the high-frequency receptor cells are located.

The Human Cochlea How We Hear 17-year old girl 76-year old man
Low noise exposure Normal cochlea Receptors intact 76-year old man Low noise exposure Fewer receptors but still intact 59-year old man High noise exposure Damaged cochlea Receptors destroyed Here, we show actual magnified photos of the human cochlea with various stages of damage: - The magnified photo of a cochlea from a 17 year-old girl shows nerves and receptor cells still intact (indicated by the dark areas in the first turn of the cochlea.) - The second photo of a 76 year-old shows fewer receptor cells due to aging (some white gaps in the receptor cells), but still intact. - The third photo of a 59 year-old noise exposed man shows significant destruction of the receptor cells. This third photo shows that noise damages hearing much more than aging alone, and much faster.

Safe Noise Levels Low noise Normal cochlea How We Hear
At safe noise levels, sound waves move along the cochlea without damaging receptor cells Low noise Normal cochlea (Animation timed to play automatically.) Here is a depiction of what is happening mechanically inside the cochlea. At safe noise levels, sound waves move along the cochlea without damaging the receptor cells, similar to a small car traveling around a sharp curve at low speed.

Loud Noise Levels High noise Damaged cochlea How We Hear
High noise levels damage the first turn of the cochlea – where high frequency sounds are heard…and lost High noise Damaged cochlea (Animation timed to play automatically.) In high noise, incoming sound waves strike the first bend of the cochlea with such force that they first fatigue – and eventually destroy – the receptor cells. Similar to a large truck at high speed trying to turn a curve, the incoming sound waves hit the first bend of the cochlea. The damage occurs where the high-frequency receptors are located; thus, noise causes a high-frequency hearing loss, regardless of whether the incoming sound is low-frequency or high-frequency noise.

High Frequency Sounds of Speech
How We Hear High Frequency Sounds of Speech CH S TH P F K SH In speech and conversation, these are the sounds that are first affected by a noise-induced hearing loss --- they will be muffled, compared to other sounds of speech. T H

Normal Hearing is Understandable
How We Hear Normal Hearing is Understandable LOUDNESS LOUDNESS Here is a visual example of noise-induced hearing loss. A viewer standing far away might not be able to see the word in the middle of the screen – LOUDNESS. [<Space> to make the word appear larger, and thus clearer.] Simply by making the word larger, it becomes clearer and easier to understand. But noise-induced hearing loss does NOT operate the same way …

NIHL Lacks Clarity How We Hear
With noise-induced hearing loss, making words louder does not necessarily make them clearer. Because this slide was intentionally made out of focus, it does not matter how big we make the word CLEARNESS (<space> to make larger) – it will never be clear. The same is true of noise-induced hearing loss – simply turning up the volume does not make speech clearer. With a noise-induced hearing loss, the clearness of speech is affected, and simply turning up the volume does not solve the problem.

Indicators of NIHL Time-linked to noise exposure
How We Hear Indicators of NIHL Time-linked to noise exposure High-frequency hearing loss Usually bilateral (both ears) Gradual progression over time Appropriate symptoms (tinnitus, muffled hearing) There are many other causes for hearing loss besides noise – ear infections, diving accidents, aging. So if somebody has a hearing loss, how can we tell whether it is caused by noise? Here are the five common indicators of noise-induced hearing loss: 1) It is time-linked to the noise exposure. There is no delayed effect in noise damage. 2) It is almost always a high-frequency hearing loss. 3) It is usually bilateral (affects both ears equally). There are some exceptions to this (for example, a truck driver who always has his right window down will have more noise exposure in the right ear than the left ear). But for employees who are on their feet during the workday, the hearing loss is usually in both ears equally. 4) Gradual progression. We don’t measure hearing loss due to noise in terms of days or weeks. It usually takes us years to notice the permanent change in hearing. 5) Appropriate symptoms. If a worker tells us he has pain in his ears, or drainage from his ears, this is probably NOT due to high noise levels. But ringing in the ears (tinnitus) is a common symptom that goes hand-in-hand with noise-induced hearing loss.

Audiometric Testing A measure HC Program effectiveness
How We Hear Audiometric Testing A measure HC Program effectiveness Measures effectiveness of HPDs Catches NIHL in its early stage Noise damage can only be determined when audiograms are compared serially A single industrial audiogram cannot identify noise damage Audiometric testing is the acid test of whether a Hearing Conservation Program is effective. Annual audiograms are compared back to each employee’s baseline audiogram to determine if a significant shift in hearing has occurred (a 10 dB average shift at Hz in either ear). If a shift occurs, and is found to be due to noise exposure, the employee must be retrained/refit with hearing protectors.

Annual Audiogram vs. Baseline
How We Hear Annual Audiogram vs. Baseline This sample shows an employee’s annual audiogram compared to his baseline audiogram (blue for left ear, red for right ear). This employee has a mild hearing loss which appears noise-related. Red arrow shows an example of a Standard Threshold Shift (STS) – an average shift of 10 dB or more at 2000 – 4000 Hz in either ear. Worker Profile 35 years old Works in Tire Shop, does not use hearing protection Early detection of noise-related hearing loss Employee retrained in the use of hearing protectors

Hearing Protection Selection

Earplugs PRO Comfortable for extended use Disposable earplugs available Cooler in hot/humid environments Single-use foam plugs can provide highest levels of attenuation CON Attenuation highly dependent upon good fit Hygiene issues in dirty environments Advantages / disadvantages of earplugs.

Earplugs CARE/MAINTENANCE Dispose single-use earplugs daily Clean multiple-use earplugs with mild soap and water, dry thoroughly Inspect multiple-use earplugs for dirt, cracks or hardness, replace if damaged Use and care of earplugs.

Bands PRO Very convenient for intermittent noise Readily available around neck when not in use CON Lower attenuation than most earplugs Some noise transmission through band Advantages / disadvantages of banded hearing protectors.

Bands CARE/MAINTENANCE Clean and replace pods regularly Do not overstretch band Use and care of banded earplugs.

Earmuffs PRO Easy to get proper fit Good for intermitten noise Radio & electronic options CON Can feel hot/heavy with extended wear Compatibility with other PPE? Advantages / disadvantages of banded hearing protectors.

Earmuffs CARE/MAINTENANCE Clean ear cushions and headband regularly with mild soap and water Replace ear cushions and foam inserts every 4-6 months with normal wear, more often with heavy use/extreme conditions Do not overstretch headband Use and care of banded earplugs.

Hearing Protection Selection Factors Comfort 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 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 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 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. 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 Noise Reduction Size Communication Job Requirements NOTE: WHEN YOU PLAY THIS SLIDE IN SLIDESHOW, EACH LISTING ON THE LEFT WILL HAVE A CORRESPONDING EXPLANATION ON THE RIGHT There are many factors that are important for the selection of the right hearing protector. COMFORT – Comfort is one of the most important because if an HPD is uncomfortable, people won’t wear it. And we all know how much noise reduction you get from a hearing protector you aren’t using: 0 dB !!! In a NIOSH study, workers cited communication as the number 1 reason for not using HPDs. 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. NOISE REDUCTION – 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. SIZE – 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. COMMUNICATION – Keep workers connected to their environment. Uniform attenuation allows speech/signals to be hear more naturally. Sound amplification earmuffs for workers with hearing impairment. The issues with communication can be solved by having the right about of noise reduction, using flat attenuation earplugs or earmuffs such as Clarity, or with communication earmuffs or Impact earmuffs depending on the environment. JOB REQUIREMENTS – Consider job requirements in HPD selection. Detectable earplugs for process industries. Hi-visibility earmuffs for dark/high traffic areas. dielectric HPDs for electrical environments. HYGIENE – 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 USE WITH OTHER PPE – Avoid compromising overall safety when wearing other PPE. Cap-mounted earmuffs for hard hats. Multiple-position earmuffs for full-brim hard hats. Ultraslim neckband earmuffs with welding shields. Hygiene Use with Other PPE

Selection Factors The Howard Leight Hearing Protector Selector makes it easy to choose the appropriate earplug or earmuff for your situation. Simply identify your requirements and preferences, and we’ll recommend a range of solutions.

Who would buy sunglasses so dark that you couldn’t see the cars coming down the road? No one! Who would buy earplugs so effective that you couldn’t hear a forklift truck coming up behind you or a distant shouted warning? Everyone…at least every industrial buyer. We’ve trained them so! Choosing the highest NRR is not the best method of selecting hearing protectors. The amount of protection should be appropriate for the amount of hazardous exposure.

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 HPD may be removed 85 80 75 70 Worker Exposure in the Ear With Protectors dB Insufficient Protection This ISO Guideline helps identify the potential problem of Overprotection. If noise levels under the hearing protector are brought below 70 dB, then some workers may feel isolation, unable to hear verbal communication nor warning alarms. Acceptable Protection Optimal Protection Acceptable Protection Possible Overprotection

Common Objections to Wearing HPDs “I already lost some of my hearing, so why should I wear them?” “Won’t I get an ear infection?” “Hearing protectors are uncomfortable to wear.” “I don’t need them! I am used to the noise.” “I can’t hear my co-workers if I wear them.” “Can I hurt my eardrums if I insert an earplug to deeply.” NOTE: THE RESPONSES TO THE OBJECTIONS LISTED ON THE SLIDE ARE HERE IN THE NOTES SECTION. This slide can be used to address common worker complaints about hearing protectors, with the following responses: - Even if you have lost some hearing, it is critical to prevent further hearing loss by wearing HPDs. - The ear cannot ‘get accustomed to noise’. Instead, this may be a sign of a mild hearing loss developing. - If uncomfortable, find an HPD style that is more comfortable for extended wear. A properly-fit HPD should feel comfortable for all-day use. - Earplugs are designed to insert at a safe distance from the eardrum. You will not damage eardrum by hearing HPDs. - An earplug does not cause ear infections, but it may aggravate an existing ear infection. If you suffer from a current ear infection, switch temporarily to earmuffs until the infection heals. - Users of HPDs will hear sounds differently (co-workers’ voices, machinery, etc.). But HPDs reduce the background noise level as well as the signals you want to hear. It may require some adjustment period, but most users find they can still hear the signals they want to hear, even while wearing HPDs. - Hearing aids are no substitute for normal hearing, and HPDs should be worn to prevent hearing loss. “I can always get fit with a hearing aid.” “My machine sounds different.”

In the United States, 76% of noise-exposed workers need no more than 10 dB of protection. 90% need no more than 15 dB of protection. The vast majority of workers in the U.S. need no more than 10 dB of real protection, and 90% need no more than 15 dB of protection, according to NIOSH data.

If workers already have hearing loss, are they exempt from using hearing protection ? According to OSHA interpretation, Hearing Conservation regulations apply to ALL employees, even those with existing hearing loss. Hearing aids alone are terrible protectors Use hearing aids + electronic earmuffs Use hearing aids + uniform attenuation earmuffs Tips for Employees Wearing Hearing Aids If workers already have hearing loss, are they exempt from using hearing protection ? According to OSHA interpretation, Hearing Conservation regulations apply to ALL employees, even those with existing hearing loss. Tips for Employees Wearing Hearing Aids Hearing aids alone are terrible protectors Use hearing aids + electronic earmuffs Use hearing aids + uniform attenuation earmuffs

50 45 40 35 30 25 20 15 10 5 63 125 250 500 1000 2000 4000 8000 Frequency in Hz Attenuation in dB Variation in attenuation is only 5 dB in speech range ( kHz) Speech will sound more natural with this earplug UNIFORM ATTENUATION This slide shows the difference in attenuation curves between a conventional earplug (shown in orange color), and a new earplug with a flat attenuation response (shown in blue). (<space> to explain uniform attenuation) The blue earplug obviously has a flatter attenuation curve than the orange earplug, especially in the critical frequency range for understanding speech (250 to 4000 Hertz). Speech and warning signals will sound more natural when using this earplug with uniform attenuation, when compared with a conventional earplug. Uniform Attenuation Earplug Conventional Earplug

Noise Reduction Rating (NRR)

Noise Reduction Rating
Noise Level = 100 dB Noise Reduction Rating = dB How much noise is reaching the ear of the worker ? Confusion about the proper application of a hearing protector’s rated attenuation has led to many to assume that most workers obtain protection at a level that equals noise minus NRR. But the amount of noise reaching the eardrum of a particular worker is completely unknown. That is completely unknown … (55 – 104 dB)

Factors in Achieving the NRR 1.FIT 2. WEAR TIME 30 dB A worker who selects an earplug with an NRR of 30 5 min 10 min 15 min 30 min but then removes that HPD for just … effectively reduced his 8-hour NRR to just … Regardless of which HPD is selected, there are two factors that determine whether an employee in the real-world will achieve the laboratory NRR: Fit, and Wear Time. This slide addresses wear time (fit will be discussed a bit later). This slide shows examples of a user who removes his HPD for just 5 minutes (cumulative) in an 8-hour workday. In noise exposures, small intervals of no protection quickly void large intervals of adequate protection. [<space> to show the effect of removing HPD for 10/15/30 minutes per workday] If a worker selects an earplugwith 30 dB of rated protection, but then removes that earplug for just 30 minutes cumulative in his 8-hour workday, it is as though he is only wearing a protector rated with an NRR of 18 dB. 26 dB 24 dB 22 dB 18 dB In noise exposures, small intervals of no protection quickly void large intervals of adequate protection.

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 Noise Reduction Rating is a laboratory estimate of the amount of attenuation achievable by 98% of users when properly fit. It is 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 – Determining an NRR
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 Hearing protectors are tested in a laboratory sound room which is intended to simulate a typical noisy setting in industry. Subjects are tested with ears open (no hearing protectors) and occluded (with hearing protectors), and the difference between those measurements is the noise reduction of the HPD. The attenuation measurements for all subjects are then input into a formula (the measurements are logarithmically added, two standard deviations are subtracted to account for variability, and 3 dB is subtracted to account for the different noise spectrums in industry). The result is the Noise Reduction Rating (NRR). A test subject in the Howard Leight Acoustical Lab, San Diego, CA, accredited by the National Voluntary Laboratory Accreditation Program (NVLAP)

De-Rating Methods OSHA NRR ÷ 2 (feasibility of engineering controls) NIOSH Earmuffs NRR – 25% Formable Earplugs NRR – 50% All Other Earplugs NRR – 70% CSA Class A up to 100 B up to 95 C up to 90 The mistrust of NRRs has led to the promulgation of several de-rating schemes. But once again, none of these does anything to predict the individual protection to be expected from a particular user.

Noise Reduction Rating –
Real-World Attenuation ≠ NRR Real user attenuation <0 to 38 dB 192 users of a flanged reusable earplug ~ 27 NRR 50 NRR = 27 Multiple-Use Earplug 40 30 Retraining and refitting resulted in an average 14 dB improvement for this group Attenuation in dB 20 There is quite a bit of variability in the attenuation obtained by users in the real world. This may be due to intentional factors (not inserting the HPD far enough in order to make it less intrusive, or more comfortable) or unintentional factors (improper sizing of HPD, poor seal around earmuffs, etc.). This scattergram shows the results of one study, indicating a wide variety of real-world attenuations for 192 workers wearing an earplug with a laboratory NRR of 27 dB. (<Space> to show retraining benefit.) Researchers in this study then took the workers with the lowest attenuation, and refit/retrained them in using the HPD properly. This resulted in an average 14 dB improvement in measured attenuation. The moral of the story? The effectiveness of an HPD relies heavily upon proper training and fitting by the wearer. 10 -10 From Kevin Michael, PhD and Cindy Bloyer “Hearing Protector Attenuation Measurement on the End-User”

100 dB 90 dB 80 dB 70 dB 60 dB 30 dB = 1000x 20 dB = 100x 10 dB = 10x 3 dB = 2x Small intervals of no protection in an 8-hour workday can quickly void the large intervals of adequate protection. Due to the logarithmic effect of noise exposures, removing a hearing protector providing 30 dB of protection exposes a worker to 1,000 times more noise for those unprotected minutes. 8-Hour Workday

Dual Protection For extreme noise environments, dual protection is often recommended To estimate the protected noise level, add about 5 dB to the higher NRR protector. EARPLUG EARMUFF + = DUAL PROTECTION In extreme noise environments (over 105 dB TWA), it is advisable to use dual protection. But to estimate the protected noise level with dual protection, the NRRs of each protector cannot simply be added. There is a ‘ceiling effect’ to the Noise Reduction Rating – a limit to the amount of protection we can achieve due to bone conduction of sound vibrations. The effect of wearing dual protection only adds about 5 dB to the higher NRR protector. Example: Earplug = NRR 33 Earmuff = NRR 29 Total Maximum Protection = 38 dB

The EPA recently made an announcement about a proposed change to the Noise Reduction Rating [NRR] This is the first change in hearing protector regulation in nearly 30 years At the beginning of August 2009, the EPA recently made an announcement about a proposed change to the Noise Reduction Rating [NRR]. This is the first change in hearing protector regulation in nearly 30 years

80th % Minimally-trained 20th % Proficient Users The EPA has announced its intention to modify the EPA label, changing the single number rating to a two-number range. The low point on that range would represent the 80th percentile (the level that most minimally-trained users could achieve), and the high point of that range would represent the 20th percentile of protected workers (the level the some proficient users could achieve). Current NRR Label Mock-up of New Label

Rating methods are based upon idealized laboratory testing NRR has been criticized for being too generous in its prediction of noise reduction [attenuation] Studies indicate that while some workers in real-world worksites achieve the NRR on the package or even greater protection, many workers do not This has led to a variety of inappropriate de-rating methods for hearing protectors Contributed too much confusion in knowing how to accurately estimate a HPD’s attenuation As background, attenuation rating methods are based upon idealized laboratory testing. NRR has been criticized for being too generous in its prediction of noise reduction [attenuation]. Studies indicate that while some workers in real-world worksites achieve the NRR on the package or even greater protection, many workers do not. This has led to a variety of inappropriate de-rating methods for hearing protectors. Contributed too much confusion in knowing how to accurately estimate a HPD’s attenuation.

The New System: A Range Represents a range of expected protection Uses a new ANSI-standard lab testing to generate the attenuation ratings New NRR will provide an indication of how much attenuation minimally-trained users [the lower number] versus highly-motivated trained users [the higher number] can be expected to achieve For some hearing protectors, the spread of this range may be quite significant The EPA has proposed changing the Noise Reduction Rating [NRR] from a fixed number to a range of attenuation. Represents a range of expected protection. This new NRR uses a new ANSI-standard lab testing to generate the attenuation ratings. The new NRR will provide an indication of how much attenuation minimally-trained users [the lower number] versus highly-motivated trained users [the higher number] can be expected to achieve. For some hearing protectors, the spread of this range may be quite significant.

Current vs. Proposed NRR Current NRR Proposed NRR Rating A single-number estimate of protection A high/low range of estimated protection Description of Rating Estimates the 98th percentile of protection obtained by users when properly fitted Estimates the 80th and 20th percentile of protection obtained by users Test Protocol ANSI S [Experimenter Fit] 10 subjects for earplugs and earmuffs, HPDs fit by experimenter ANSI S Method A [Supervised Subject-Fit] 20 subjects [for earplugs] or 10 subjects [for earmuffs], HPDs fit by subject after brief training This slide demonstrates the differences between the current and proposed NRR.

Current vs. Proposed NRR Current NRR Proposed NRR Application Intended for use with dBC noise measurements Requires a 7 dB correction for use with dBA noise measurements. Can be applied directly to dBA noise measurements De-Rating Various de-rating schemes promulgated by various organizations [including OSHA] Designed to be used with no required de-rating Retesting Currently, no retesting of HPDs required Periodic retesting of HPDs required every 5 years

NRR Labels The proposed EPA regulation addresses for the first time the rating of non-standard hearing protectors, such as Active Noise Reduction [ANR] or level-dependent [or impact noise] protectors Under the old labeling requirements, these specialized protectors were rated with a low NRR, simply because they were not tested in the higher noise ranges where their noise reduction capability is activated EPA has included these types of hearing protectors in its new labeling regulation so that purchasers can make informed choices The proposed EPA regulation addresses for the first time the rating of non-standard hearing protectors, such as Active Noise Reduction [ANR] – such as noise cancellation headsets used during travel - or level-dependent [or impact noise] protectors – such as Impact Sport-styled earmuffs. Under the old labeling requirements, these specialized protectors were rated with a low NRR, simply because they were not tested in the higher noise ranges where their noise reduction capability is activated. EPA has included these types of hearing protectors in its new labeling regulation so that purchasers can make informed choices.

Three New Labels LABEL DESCRIPTION Conventional HPD Perform lab test with subjects who fit the protector after brief training Estimates the range of protection achieved by 20% and 80% of users Active Noise Reduction [ANR] Uses a Microphone-in-Real-Ear [MIRE] method to estimate protection Measured with ANR turned OFF and ON to show the additional attenuation from the ANR Level Dependent/ Impulse Noise Reduction Testing will occur over a range of impulse noise levels. Multiple tests to determine lower and upper ranges of impulse noise reduction Will include two ranges to identify attenuation for passive and active modes This slide covers the three new proposed labels, and the different types of HPDs will be tested.

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% The new label will display a range of attenuation for each HPD. 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.

Why did the EPA decide to make this change? Since 1974, the EPA has used the Noise Reduction Rating as its yardstick to measure hearing protector effectiveness in reducing noise levels NRR is based upon idealized laboratory testing, many studies indicate the NRR can over-estimate the protection received by many workers The new Noise Reduction Rating will take into better consideration the human factors involved with the use of HPDs – specifically training and fit Since 1974, the EPA has used the Noise Reduction Rating as its yardstick to measure hearing protector effectiveness in reducing noise levels. NRR is based upon idealized laboratory testing, many studies indicate the NRR can over-estimate the protection received by many workers. The new Noise Reduction Rating will take into better consideration the human factors involved with the use of HPDs – specifically training and fit.

Why is a two-number range part of the new label? It is a more realistic indicator of the variety of protection levels achieved by users in the real world, depending on their training and fit In the past, some safety managers assumed that the attenuation rating on the package would be achieved by most workers, regardless of training or motivation Two-number range now clearly shows that employees who use the same HPD can obtain different levels of protection Employees who are motivated and trained to achieve a proper fit will be nearer the high end of the range A two-number range on the label is a more realistic indicator of the variety of protection levels achieved by users in the real world, depending on their training and fit. In the past, some safety managers assumed that the attenuation rating on the package would be achieved by most workers, regardless of training or motivation. Two-number range now clearly shows that employees who use the same hearing protector can obtain different levels of protection. Those employees who are motivated and trained to achieve a proper fit will be nearer the high end of the range.

Will OSHA 29 CFR change? OSHA has not announced any proposed changes to the Occupational Noise Standard OSHA will presumably respond to the revised NRR label by issuing a field directive or technical memorandum, informing its compliance officers how to deal with the new two-number NRR range OSHA has not announced any proposed changes to the Occupational Noise Standard. OSHA will presumably respond to the revised NRR label by issuing a field directive or technical memorandum, informing its compliance officers how to deal with the new two-number NRR range.

Will the new rating methods favor earplugs or earmuffs? While a well-fit foam earplug generally has greater attenuation than most earmuffs, earmuffs are inherently easier to fit for most users There is less variability in the fit of earmuffs Overall range of attenuation for earmuffs will usually be tighter and often higher, than earplugs Workers should be offered a choice of earplugs, bands and earmuffs that meet the requirements of the work environment While a well-fit foam earplug generally has greater attenuation than most earmuffs, earmuffs are inherently easier to fit for most users. There is less variability in the fit of earmuffs. Overall range of attenuation for earmuffs will usually be tighter and often higher, than earplugs. Workers should be offered a choice of earplugs, bands and earmuffs that meet the requirements of the work environment.

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 to determine if spectral balance corrections will be necessary Update HC Training Program on proper fit of hearing protectors. Hold a “Toolbox Training” and hold a refresher fit training session. 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. 1. Re-evaluate Current HPD Selection – to determine whether they are appropriate for your noise environment. Use the Howard Leight Hearing Protector Selector – - for recommendations. 2. Provide Better Training – on proper fit of hearing protectors. Hold a “Toolbox Training” and hold a refresher fit training session.

What Can I Do Now? Evaluate Current HPD Selection to determine whether they are appropriate for your noise environment. Use the Howard Leight Hearing Protector Selector for recommendations. Upgrade to One-on-One Training research studies confirm that one-on-one training is superior to group training 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. 1. Re-evaluate Current HPD Selection – to determine whether they are appropriate for your noise environment. Use the Howard Leight Hearing Protector Selector – - for recommendations. 2. Provide Better Training – on proper fit of hearing protectors. Hold a “Toolbox Training” and hold a refresher fit training session.

Earplug Fit Testing Provides an accurate, real-world picture of your employees’ hearing protector effectiveness. Identify if your employees are: Receiving optimal protection Require additional training Need to try a different earplug style Use VeriPRO fit testing to train how to properly fit HPDs, select appropriate HPDs and document adequate protection. Use QuietDose in-ear dosimetery to document the noise dose employee is exposed to during their work shift.

Earplug Fit Testing As a problem solver: Derating Schemes One-on-One Training HPD Selection NRR Change Use VeriPRO fit testing to train how to properly fit HPDs, select appropriate HPDs and document adequate protection. Use QuietDose in-ear dosimetery to document the noise dose employee is exposed to during their work shift.

In-Ear Dosimetry As a Problem Solver Employees with Documented NIHL or STS At-Risk Employees Training + Sampling Dual-Protection/ Extreme Noise Engineering Controls Use VeriPRO fit testing to train how to properly fit HPDs, select appropriate HPDs and document adequate protection. Use QuietDose in-ear dosimetery to document the noise dose employee is exposed to during their work shift.

Reducing Costs + Claims for Hearing Loss

How Can You Prevent NIHL?
Reducing Costs + Claims How Can You Prevent NIHL? Earplug Fit Testing In-Ear Dosimetry There are now two methods that allow users to measure the fit and exposure protection in the workplace” Fit Testing (using a system like VeriPRO) In-ear Dosimetry (using a system like QuietDose)

Reducing Costs + Claims
Published NRR Taken from a study of 101 workers at eight different companies, this scattergram shows how far away each worker was from the published NRR of the respective earplug they were using. About 1/3 of the workers had measured attenuation that were higher than the published NRR. About 1/3 were within the range about 5 dB below the published NRR. And about 1/3 of the workers had attenuation that was more than 5 dB below the published NRR. The bottom left photo shows the variety of earplugs that were tested in this study. This scattergram shows the danger in using de-rating policies like the oft-misapplied 50% de-rating by OSHA. If we were to summarily just assume that all earplugs only achieve 50% of the published NRR in the field, then clearly 2/3 of the workers are seriously overprotected, since they are achieving much higher protection than 50%.

Personal Factors Program Factors Reducing Costs + Claims Gender Age
Years in Noise Ear Canal Size Familiarity Model of Earplug Program Factors # Group Trainings # Personal Trainings What is the best predictor of a worker achieving good attenuation from an earplug? We looked at the following personal and program factors, and concluded there was only one strong factor that correlated with good protection: that factor was individual training. Workers who receive individual training in how to use their hearing protectors are more likely to achieve a high personal attenuation. All other factors just followed a random distribution.

REDUCING COSTS / CLAIMS
Published NRR A second important factor in achieving good attenuation in the field is the option of trying a second hearing protector. If a worker obtains low attenuation with one type of earplug, will he obtain low attenuation with all types of earplugs? Our study showed the answer is definitely NO. Workers who tried a second pair of earplugs often had major leaps in attenuation, bringing them closer to the published attenuation. Trying a second earplug often improves attenuation

REDUCING COSTS / CLAIMS
In-Ear Dosimetry as a Problem Solver Employees with documented noise-induced hearing loss or Standard Threshold Shift [STS] Employees at-risk for NIHL Employee training + sampling Dual-protection/extreme noise exposure Engineering controls There are several instances where QuietDose can improve a Hearing Conservation Program. It can be used with: Employees with Documented Noise-Induced Hearing Loss or Standard Threshold Shift [STS] Employees At-Risk for NIHL Employee Training + Sampling Dual-Protection/Extreme Noise Exposure Engineering Controls

Individual Worker/Daily Exposures
Reducing Costs + Claims In-Ear Dosimetry as a Problem Solver Individual Worker/Daily Exposures The typical sequence of measurements from in-ear dosimetry on an individual worker may look something like this. Initially, measured noise doses are quite high (over 100%). As the worker receives feedback about the overexposures, the daily noise doses work their way downward, until nearly all noise doses are below 50%. Date

Research > Alcoa Intalco Works
Reducing Costs + Claims Research > Alcoa Intalco Works In-Ear Dosimetry as a Problem Solver Mean Hearing Threshold (2k, 3k, 4kHz): – 2007 (N = 46) Employees using continuous in-ear dosimetry starting in 2005 Case Study: ALCOA Intalco (presented by Dr. Kevin Michael et.al. at AIHA 2007, used with permission)

Preventive Action After NIHL
Reducing Costs + Claims Preventive Action After NIHL In practice, an OSHA-recordable STS is not a preventive action It is documentation of a hearing loss after the fact. How soon will an employee suffering NIHL be re-fit / re-trained ? “Best case scenario” per Hearing Conservation Amendment In-ear dosimetry “worst case” scenario … 1 Day Months • Audiometric test • Retest • Notification By itself, OSHA’s Standard Threshold Shift is not a preventive measure. It documents hearing loss after the fact, and simply resets the clock for retesting without verifying whether preventive measures were successful. The annual audiogram is a “lagging indicator” of whether a Hearing Conservation Program is successful. In-ear dosimetry, however, gives users immediate feebback, allowing them to immediately adjust their protection level until they reach sufficient levels. In-ear dosimetry thus becomes a “leading indicator.”

Additional Information
Reducing Costs + Claims Additional Information OSHA Alliance: Best Practice Bulletin What does OSHA feel about fit testing systems for hearing protection? In an OSHA Alliance Best Practices Bulletin (see link), seven benefits of fit-testing systems are offered, and the concept is endorsed as a best practice for Hearing Conservation Programs.

Tools for HCP Prevention Metrics
Reducing Costs + Claims Tools for HCP Prevention Metrics PROS Estimate Measure NRR obsolete Fulfills OSHA compliance Eliminates need for de-ratings Medico-legal cases Delineates non-occupational Eliminates double protection Provides employee feedback CONS Cost Time Investment Not standardized The advantages and disadvantages of fit verification methods are described.

Off-job + On-job = STS Off-job + On-job = STS Reducing Costs + Claims
Verification of attenuation of hearing protectors on the job also gives safety managers a much-needed point of differentiation in determining causality of hearing loss. If a worker with NIHL is unprotected from hazardous noise exposures off the job, fit verification helps distinguish the On-Job versus On-Job components of that hearing loss. Off-job + On-job = STS Off-job + On-job = STS

February 25-27, 2010 Orlando, FL

Hearing Protectors + Fitting Tips

0 dB 0 dB 33 dB How much protection? Fitting Tips EAR #1 EAR #2 EAR #3
Just having an earplug in the ear is no guarantee of protection. In the photos shown here, a safety supervisor inspecting worker compliance may assume that the middle ear is protected. Actually, that worker is receiving 0 dB of protection, due to a poor fit. EAR #2 EAR #3 How much protection?

Good Fit vs Bad Fit Fitting Tips Frequency in Hz Attenuation in dB
-10 125 250 500 1000 2000 3150 4000 6300 8000 Frequency in Hz 90 80 70 60 50 40 30 20 10 Attenuation in dB Max Poor Fit NRR = 0dB Max Good Fit NRR = 33dB <space> to show two fittings of the same earplug in the same worker’s ear on the same day. In both cases, the earplug was visibly in the ear far enough to satisfy a cursory compliance check. But the difference – a good insertion versus a poor insertion – is enough to cause a 30+ dB improvement in attenuation when the earplug is deeply inserted and achieves a good seal in the ear. The worker may be lulled into a false sense of protection when, even with a poor fit, he detects a slight muffling of high-frequency sounds – some of the “edge” is taken off shrill noise. But because the poor fit has seriously compromised low-frequency attenuation, the effective overall protection is 0 dB!

Roll-Down Foam Earplugs
Fitting Tips Roll-Down Foam Earplugs 2. Pull Back pinna by reaching over head with free hand, gently pull top of ear up and out 1. Roll entire earplug into a crease-free cylinder 3. Insert earplug well into ear canal and hold until it fully expands For earplugs, effective protection is dependent upon a deep insertions. With foam earplugs, this is accomplished by following these three steps: - Roll down the foam earplug to a small crease-free cylinder - Straighten out the bend in the ear canal by reaching over the head with the free hand, and pulling the ear up and out. - Insert the earplug well into the ear canal and hold it in place a few seconds while the foam fully expands

Multiple-Use Earplugs
Fitting Tips Multiple-Use Earplugs 1. Reach While holding the stem, reach hand overhead and gently pull top of ear up and back. 2. Insert Insert earplug so all flanges are well inside the ear canal. 3. Fit If properly fitted, only the stem of the earplugs should be visible to someone looking at you from the front. Steps for proper insertion of no-roll foam earplugs. Steps for proper insertion of multiple-use earplugs. (see Howard Leight fitting poster, available free of charge)

Visual + Acoustical Checks
Fitting Tips Visual + Acoustical Checks 2. Acoustical Check Cup hands over ears and release. Earplugs should block enough noise so that covering your ears with hands should not result in a significant noise difference. Visual Check The earplug should sit well inside the ear canal and not stick out. There are two ways to determine if the earplug is in far enough to provide adequate protection: 1) Visual Check. When viewed directly from the front, the end of a properly-fit earplug should not be visible. 2) Acoustic Check. Cup your hands tightly and place them over your ears, then release. When earplugs are properly fit and doing their job, there should be no noticeable change in the noise level. If the earplugs are not inserted far enough, there will be a noticeable change in the noise when hands are cupped over the ear.

Earmuff Instructions Fitting Tips Place earcups over each outer ear
2. Adjust the headband by sliding the headband up or down at the attachment buttons 3. The ear cushions should seal firmly against the head Steps for proper fitting of earmuffs. (see earmuff fitting poster, available free of charge)

Fitting Instruction Posters
Fitting Tips Fitting Instruction Posters Howard Leight offers earplug and earmuff fitting instruction posters at no charge. PDFs can also be found at

FAQ: Earmuffs + Safety Eyewear
Fitting Tips FAQ: Earmuffs + Safety Eyewear In our facility, several noisy areas require safety eyewear as well as earmuffs. Can earmuffs be worn over safety eyewear without affecting attenuation? Many worksites require safety eyewear. Does wearing an earmuff over safety eyewear break the seal, and reduce attenuation of the earmuff? From testing performed on five different models of safety glasses with different models of earmuffs, we find that the effect upon attenuation is mostly dependent upon the width of the eyeglass frame where it meets the earmuff cushion. When that temple arm of the frame is wide (5-6 mm), it can cause leakage resulting in a decline of 5 dB or more in the NRR. But when that temple arm is thin (1-2 mm), the effect on attenuation is negligible. (full report of this study is available on > Tools to Learn > Sound Source #2A Affect on Attenuation Thin Frame (1-2 mm) 0 dB Medium Frame (3-4 mm) 2 dB Thick Frame (5-6 mm) 5 dB Attenuation is impacted significantly by thick-framed eyewear.

Fitting Tips FAQ: Dual Protection At our facility, we are exposed to extreme noise levels and wear both earplugs and earmuffs. How much reduction in noise level can we expect from dual protection? In extreme noise environments (over 105 dB TWA), it is advisable to use dual protection. But to estimate the protected noise level with dual protection, the NRRs of each protector cannot simply be added. There is a ‘ceiling effect’ to the Noise Reduction Rating – a limit to the amount of protection we can achieve due to bone conduction of sound vibrations. The effect of wearing dual protection only adds about 5 dB to the higher NRR protector. Max® earplug dB Viking™ earmuff dB Maximum Protection 38 dB To estimate protected noise level, add 5 dB to the higher NRR protector.

FAQ: Earmuffs + Absorbent Pads
Fitting Tips FAQ: Earmuffs + Absorbent Pads We work in a humid environment and use moisture-absorbing pads with our earmuffs. Do the pads affect the attenuation of the earmuff ? In hot or humid environments where the absorbent cooling pads are used, one might ask whether the addition of the pad breaks the seal, and therefore changes the attenuation. When tested in the acoustical lab, we found no significant change in attenuation with the addition of the absorbent pads. (full report of this study is available on No significant affect on attenuation!

FAQ: Radio Earmuffs + Noise
Fitting Tips FAQ: Radio Earmuffs + Noise Is it safe to use earmuffs with built-in AM-FM radios? Doesn’t the radio just add more noise to damage hearing ? Radio and electronic earmuffs have circuitry that limits the amount of amplification to a safe level of 82 dB. No matter how high the volume is adjusted on these earmuffs, the output will be limited to 82 dB. When used in hazardous noise, the extra noise caused by the addition of radio noise generally does not pose any increased risk. As shown in the hypothetical example, the protected noise level while using an electronic earmuff can still be a safe exposure. (full report of this study is available on > Hearing Conservation > Sound Source #3A) Noise Level Under Earmuff Ambient Noise dB Attenuation dB Passive Exposure = 80 dB Plus Radio Noise dB Effective Exposure 84 dB Built-in sound level limitation circuitry can mitigate additional noise exposure risks.

FAQ: Active Noise Cancellation
Fitting Tips FAQ: Active Noise Cancellation What about Active Noise Cancellation (ANC) earmuffs? Inserts a reverse-phase signal to cancel incoming noise Noise reduction at frequencies below 500 Hz Most effective in continuous noise (commuter noise) Not cost-effective for workers A recent innovation in noise reduction comes from headphones with Active Noise Cancellation (ANC). These reduce the perceived noise by inserting a reverse-phase signal to cancel incoming noise. But the noise reduction is only effective in continuous noise at frequencies below 500 Hz. The limited application and high cost means they are rarely used among industrial workers.

FAQ: Custom Molded Earplugs
Fitting Tips FAQ: Custom Molded Earplugs What about Custom Molded Earplugs? PRO Comfort Personal attachment CON Lower attenuation Variability in attenuation Lubricant required No extended-life benefit Custom-molded earplugs are now available in the industrial market. These products require an impression to be made of each ear, which is sent to a processing lab to make a molded earplug (usually made of silicone or acrylic). The cost, including taking the impressions, is often $80-$100 per pair. We invited 40 test subjects to the Acoustical Lab at Howard Leight Industries to obtain custom-molded earplugs, then tested the attenuation on each one. While nearly all subjects found them to be comfortable, the measured attenuation was much lower than conventional earplugs. Surprisingly, we also found the consistency of that attenuation (from one day to the next) was no better than conventional earplugs. The bottom line is that the same benefits claimed for custom-molded earplugs can be obtained with conventional earplugs at a fraction of the cost.

Training + Motivation

Personalize Hearing Loss
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? We can motivate employees to wear their hearing protection if we can prove to them that they are not invincible nor invulnerable to noise-induced hearing loss. This can be accomplished by giving workers a copy of their audiometric test, or by clearly showing workers the noise hazardous noise levels at their worksite. Getting workers to think about what their hearing means to them can help to personalize their motivation to prevent noise-induced hearing loss.

Demonstrate Future Risk
Training + Motivation Demonstrate Future Risk Training Materials atl.grc.nasa.gov/HearingConservation/Resources/index.html It is human nature to weigh our risks in terms of “here and now.” But with noise-induced hearing loss, we must show the worker the future risk. This can be accomplished by means of audio demonstrations, or simulated hearing losses, so that the worker has a clear understanding of his future risk, and the need for adequate protection today. The links listed on this slide offer great training and educational resources, including audio demonstrations, that can be used in your HC training program.

Send Clear Message On + Off Job
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 Many employers encourage their workers to use the company-provided hearing protectors off-the-job. After all, any noise-induced hearing loss (whether on- or off-the-job) will cause hearing loss which will be detected in the company-sponsored audiometric testing program. Proper use of hearing protectors both on and off the job will prevent noise-induced hearing loss. Emphasize that Hearing Conservation should be a part of everyday life, at both work and home. Include recreational HC training in your annual training. Many employers encourage their workers to use the company-provided hearing protectors off-the-job. After all, any noise-induced hearing loss (whether on- or off-the-job) will cause hearing loss which will be detected in the company-sponsored audiometric testing program. Proper use of hearing protectors both on and off the job will prevent noise-induced hearing loss.

Remove Barriers to HPD Use
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 Compliance in wearing hearing protection will be greatest when we remove the barriers or excuses that employees may raise as objections. Is an adequate supply of hearing protectors available? Is there a reasonable selection of comfortable protectors for workers? Does the amount of attenuation match the noise level? 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

Hearing Loss Due To Noise Exposure Is … Painless Permanent Progressive
Training + Motivation Hearing Loss Due To Noise Exposure Is … Painless Permanent Progressive … and very Preventable!

HearForever: Best Practices in Hearing Conservation

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