Hearing Conservation Theresa Y. Schulz, PhD, LtCol, USAF (ret.)

Hearing Conservation Theresa Y. Schulz, PhD, LtCol, USAF (ret.)

Selecting Hearing Protection
Topics The Amazing Ear Selecting Hearing Protection Noise Reduction Hearing Protection Fitting Tips 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. Motivating Workers

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 Protection Selection

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

Hearing Protection Selection – Earplugs
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.

Hearing Protection Selection – Banded Earplugs
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.

Hearing Protection Selection - Earmuffs
Easy to get proper fit Good for intermittent noise Radio & electronic options CON Can feel hot/heavy with extended wear Compatibility with other PPE? Advantages / disadvantages of earmuffs

Hearing Protection 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. ”

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 dB dB Insufficient Protection 85 80 75 70 85 80 75 70 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 Worker Exposure in the Ear With Protectors Optimal Protection Acceptable Protection Possible Overprotection

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

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.

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)

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.

NVLAP-Accredited Labs Howard Leight Acoustical Lab, San Diego, CA Indianapolis, IN State College, PA There are currently three acoustic laboratories accredited by the National Voluntary Laboratory Accreditation Program (NVLAP) for testing hearing protectors against the EPA-required standard (ANSI S ).

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)

NRR Noise Reduction Rating – Determining an NRR NRR
5 4 Number of test subjects 3 2 30 Subject test results (10 x 3) 1 14 18 20 22 24 26 28 30 32 19 23 25 27 Attenuation

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 Fit Test 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”

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.

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 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).

New NRR (NRsa) 80% achieved > 20 dB 20% achieved > 26 dB
5 4 Number of test subjects 3 2 40 Subject test results (20 x 2) 1 11 14 18 20 22 24 26 28 30 33 19 23 25 27 Attenuation

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.

Biggest Factors in Achieving 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 … 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. effectively reduced his 8-hour NRR to just … 26 dB 24 dB 22 dB 18 dB In noise exposures, small intervals of no protection quickly void large intervals of adequate protection.

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

Reducing Costs of Hearing Loss
OSHA Alliance: Best Practice Bulletin Additional Information 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.

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

Fitting Tips

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: Hearing Aids / Protection
Fitting Tips FAQ: Hearing Aids / Protection Can hearing aids act as hearing protectors? Hearing aids alone are often poor hearing protectors Use hearing aids and electronic earmuffs Use hearing aids and uniform attenuation earmuffs

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 Variable 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 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.

Training + Motivation 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 Music etc. 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
… and very Preventable!

Hearing Conservation Theresa Y. Schulz, PhD, LtCol, USAF (ret.)

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Hearing Conservation Theresa Y. Schulz, PhD, LtCol, USAF (ret.)

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