Non-electronic Level-dependent Hearing Protectors

Non-electronic level-dependent hearing protectors use an acoustic filter to reduce noise exposure while maintaining the wearer's ability to hear speech and alarm signals. 

Description:

Non-electronic level-dependent hearing protectors (NELDHPs) help reduce hearing loss and tinnitus due to noise overexposure without blocking important sounds like coworkers' voices or backup alarms. Traditional (passive) hearing protectors reduce noise at the ear canal uniformly across all levels.  In contrast, NELDHPs block noises above a certain level. As impulsive sounds become louder, the valves in these style of ear plugs become more effective at blocking harmful noise. NELDHPs will attenuate frequencies differently from typical passive foam or premolded ear plugs.

NELDHPs perform a similar function to electronic level-dependent hearing protectors (ELDHPs), but they work through a different mechanism. While ELDHPs use a microphone to pick up sounds and then reproduce them electronically inside the ear canal at a safe volume, NELDHPs use a special membrane called an acoustic filter. This filter sits within the hearing protection device. All noise must pass through it on the way to the listener’s ear canal. The filter is air permeable, which improves ventilation and may increase the user’s comfort.

Many brands of NELDHPs have removable filters for maximum utility. When the filter is taken out and replaced with a plug, the listener receives the same protection they would get from a similar hearing protection device like a standard rolled or molded earplug. If the filter is removed and the channel between the general environment and the ear canal is left open, the listener does not receive any hearing protection.

 

3M Combat Arms Ear Plugs

  • Cost: $16.96
  • Noise Reduction Rating (NRR): 7-23
  • Material: elastomeric polymer

Source: www.3m.com

 

Earmonix Industrial and Home Improvement Ear Plugs

  • Cost: $21.88
  • NRR: 16
  • Material: thermoplastic elastomer (TPE)

Source: earmonix.net

 

Moldex BattlePlugs Impulse Protection Ear Plugs

  • Cost: $11.76
  • NRR: 9-24
  • Material: thermoplastic elastomer (TPE)

Source: www.moldex.com

 

Surefire EP7 Sonic Defenders® Ultra

  • Cost: $19.95
  • NRR: 28
  • Material: memory foam

Source: www.surefire.com

 

Westone DefendEar Hunter Passive Ear Plugs

  • Cost: $129.99
  • NRR: 4
  • Material: silicone

Source: www.westone.com

 


Risks Addressed:

Repeated overexposure to noise causes permanent hearing loss and ringing in the ears (tinnitus).  It has also been associated with hypertension and other cardiovascular diseases (Girard et al, 2015).

The Occupational Safety and Health Administration (OSHA) requires that workers’ LAeq (similar to an 8-hour time-weighted average) remain under 90 decibels, while NIOSH has recommended that it remain under 85 decibels. NIOSH’s recommendations are more protective and preferred for maximum hearing conservation. Table 1 shows how long a worker can safely be exposed to different levels of noise (measured in A-weighted decibels, or dBA) according to both OSHA and NIOSH criteria.

 

dBA

OSHA

NIOSH

80

32 hours

>24 hours

85

16 hours

8 hours

90

8 hours

2.5 hours

95

4 hours

47.6 minutes

100

2 hours

15 minutes

105

1 hour

4.7 minutes

110

30 minutes

1.5 minutes

115

15 minutes

28 seconds

120

7.5 minutes

9 seconds

125

3.8 minutes

3 seconds

Table 1


How Risks are Reduced:

NELDHPs prevent hearing loss by blocking harmful levels of noise from entering the ear canal. They are similar to non-level dependent (passive) forms of hearing protection in shape and size, but they block noise selectively. NELDHPs use a special membrane to filter out louder noises. This means that the user’s hearing is protected without masking lower-level noises that are important for safety and communication, such as back-up alarms and coworker’s voices. While softer noises are often muffled by traditional passive hearing protection like foam ear plugs, a 2011 study confirmed that NELDHPs preserve the wearer’s ability to understand normal speech (Norin, Emanuel & Letowski, 2011).

Many tools frequently used in the construction industry, like powder-actuated nailers and pneumatic nail guns, produce high level impulse noise, which is loud but short in duration. This kind of noise has been shown to cause more damage to hearing than equivalent levels of continuous noise (Starck, Toppila & Pyykkö, 2003). If you are exposed to impulse noise, it is especially important to wear appropriate hearing protection. NELDHPs have been shown to reduce the impact of impulse noise on workers' hearing (Fackler, Berger, Murphy & Stergar, 2017). Workers may also be more likely to consistently use hearing protection that does not interfere with their ability to hear coworkers and alarm signals.  


Effects on Productivity:

n/a


Additional Considerations:

Noise Reduction Ratings (NRR) are based on laboratory tests that may not fully represent real-world conditions. OSHA recommends “derating” the published NRR on hearing protection devices to adjust from C-weighted noise levels to A-weighted noise by subtracting seven. This derated value can be subtracted from an A-weighted noise exposure measurement to estimate the noise level that reaches the ear.

Hearing protection devices should be used as a last resort when substitution, elimination, and engineering controls are not achievable. Buying quieter tools and machinery can eliminate the need for hearing protection. Administrative controls and work practices can also be used to reduce the amount of time any one employee spends in a noisy area. If these practices are not sufficient to reduce workers’ noise exposure to 85 decibels or less, employers must provide appropriate hearing protection devices as part of a written hearing conservation program.


Contributors:

Sara Brooks, MPH, CPH - CPWR The Center for Construction Research and Training
William J. Murphy, Ph.D. - NIOSH


Hazards Addressed:

  • Carpentry
    • Build or install roof trusses
    • Construct forms for concrete footings and foundations
    • Construct suspended ceiling interior systems
    • Cut boards and panels
    • Fit and nail exterior walls and roof sheathing
    • Frame floors, walls, ceiling, stairs and roofs using wood and/or metal studs and door bucks
    • Install and finish wood flooring
    • Install cabinets, countertops and moldings
    • Install doors, windows and associated hardware
  • Drywall, Glass & Floor Coverings
    • Cut and install metal framing for windows and atriums
    • Cut boards and panels
  • Electrical
    • Cut, shape, place and install conduit and wire trays
    • Install and maintain electrical control systems
    • Install and maintain fixtures, lights, motors and pumps
    • Install interior wiring systems
  • Excavation & Demolition
    • Chip, break and recycle concrete
    • Clear and grub site
    • Deconstruct building foundations
    • Deconstruct superstructures
    • Drill rock and concrete and install tie backs
    • Excavate sites
    • Jackhammer concrete surfaces
    • Perform flame or plasma cutting
    • Rig, load and transport components debris
    • Secure and demolish damaged structures
  • General Labor
    • Compact earth
    • Install traffic control markers, barricades and maintain traffic patterns
    • Jackhammer rock and concrete surfaces
    • Operate concrete mixers, pumps and fire proofing sprayers
    • Operate earth boring machines
    • Operate pavement cutters and concrete grinders
    • Pave and patch concrete and asphalt
    • Perform manual demolition
  • Heavy Equipment
    • Compact earth
    • Construct and refurbish concrete and asphalt roadways
    • Demolish and recycle structures
    • Maintain heavy equipment
    • Operate earth-moving equipment
    • Operate stationary equipment
    • Operate transport equipment
    • Operate within traffic and work zones
    • Rig, load and transport materials and equipment
    • Survey sites for elevation and grade
  • Insulation & Lagging
    • Blow and place insulation
    • Install and apply fire stop products
    • Maintain and remove old insulation including asbestos
    • Spray fireproofing onto columns and beams
  • Masonry, Tile, Cement & Plaster
    • Chip, scrape and grind surfaces, or joints
    • Cut bricks, blocks, stone, concrete, tile or terrazzo
    • Drill holes and install reinforcing rods and anchors
    • Mix cement, mortar, plaster, or grout
    • Pour cement, mortar, plaster, or grout
  • Paints & Coatings
    • Perform abrasive blasting
    • Pressure wash, and use chemicals for surface prep and stripping
  • Pipes & Vessels
    • Assemble pipes, tubing and fittings
    • Assemble vessel structures and parts
    • Cut and drill holes in structures prior to pipe installation
    • Cut, thread, hammer and bend pipes and vessel tubes
    • Deburr and grind pipes and vessel tubes
    • Disassemble and remove damaged or worn pipe
    • Install pipe assemblies, fittings, valves, appliances and fixtures
    • Mount brackets and hangers on walls and ceilings to hold pipes
    • Weld, braze, solder, cut, or gouge pipe sections or vessel parts
  • Reinforced Concrete
    • Cut or bend rebar
    • Drilling concrete
    • Finish concrete
    • Mix concrete
    • Perform surface grinding or cutting
    • Prepare and chip surfaces
  • Residential Construction
    • Clear and grade
    • Cut boards and panels
    • Install and finish flooring
    • Install cabinets, countertops and moldings
    • Install doors, windows, attic access and associated hardware
    • Install framing and roof trusses
    • Install roofing shingles or tiles
    • Perform surface grinding or cutting
    • Pour, pump and vibrate concrete
  • Roofing
    • Cut tiles
    • Install asphalt roofs
    • Install roof sheathing
    • Install tile or shingle roofs
    • Remove old roofing materials
  • Sheet Metal & HVAC
    • Assemble fittings and fasten seams and joints using hand and power tools
    • Cut, file, grind, deburr, buff and smooth assembled parts
    • Install heating and air conditioning duct hangers and ductwork
    • Layout, shear, drill and punch holes in metal
    • Operate laser cutter and metal shearing machine
    • Operate metal press, hand brake and forming machines
    • Rig and set HVAC equipment with cranes, helicopters, hoists and lifts
    • Shape metal material over anvils, blocks or other forms
    • Weld, braze and solder seams and joints
  • Structural Steel
    • Build or erect false work
    • Dismantle or demolish metal structures
    • Drill, grind and saw materials
    • Erect and dismantle scaffolds
    • Erect stairways, curtain walls, wire rope railings
    • Fabricate metal structures in shop and field
    • Hoist and move members and components in shop
    • Install exterior skin
    • Load and unload material, members and components
    • Place and connect structural members
    • Rig and hoist structural members and machinery
    • Unload, assemble, jump and disassemble cranes
    • Weld, plasma cut, air-arc and flame cut metal

Availability

Earmonix
To obtain information, visit Industrial and Home Improvement Ear Plugs

Moldex
To obtain information, visit BattlePlugs Impulse Protection Ear Plugs

Surefire
To obtain information, visit EP7 Sonic Defenders® Ultra

3M
To obtain information, visit Combat Arms Ear Plugs

Westone
To obtain information, visit DefendEar Hunter Passive Ear Plugs

Return on Investment

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