Solution Summary: Electronic Level-Dependent Hearing Protectors
Electronic level-dependent hearing protectors prevent hearing loss due to noise overexposure while maintaining users’ awareness of lower-level speech and alarm signals.
Description:
Electronic level-dependent hearing protectors (ELDHPs) help reduce hearing loss and tinnitus due to noise overexposure without completely blocking quieter sounds like coworkers’ voices or backup alarms. Traditional (passive) hearing protectors reduce noise at the ear canal uniformly across all levels. In contrast, ELDHPs reduce loud noises that can damage hearing while amplifying softer sounds that can be important for safety and communication.
Most models of ELDHPs allow the wearer to adjust the output volume. Some more recent models have built-in radios or Bluetooth connections so the need to wear hearing protection does not interfere with electronic communication.
Elvex Com-655
- Style: headband
- Noise Reduction Rating (NRR): 25
- Connectivity: audio jack (listen only)
- Power: two 1.5 volt AAA batteries (175 hours)
3M PELTOR LEP-200
- Style: earplugs
- Noise Reduction Rating (NRR): 23-30 depending on eartip type
- Connectivity: wireless connectivity (two-way) through a separately-sold Bluetooth neckloop accessory with an external jack
- Power: Micro USB or three AA batteries (16 hours)
3M PELTOR WS LiteCom PRO III Headset
- Style: neckband
- Noise Reduction Rating (NRR): 28
- Connectivity: Bluetooth-enabled two-way communication and external jack
- Power: rechargeable lithium-ion battery (11 hours)
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’ 8-hour LAeq 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:
Electronic Level-Dependent Hearing Protectors (ELDHPs) are similar to traditional (passive) hearing protection devices in that they protect workers’ hearing by blocking harmful levels of noise from entering the ear. However, ELDHPs reduce noise selectively. External microphones on the ELDHP sample sounds outside the protector to determine whether or not amplification is required. When sounds exceed the threshold limit for amplification (typically 82 dB), amplification is reduced to prevent transmission or reproduction of hazardous levels of noise inside the ear canal. Lower-level sounds such as speech or back-up alarms are amplified so that they will be audible without exceeding hazardous levels.
ELDHPs are especially useful for workers who have already sustained hearing loss. A 2015 study showed that while all workers showed some improvement in speech recognition while wearing ELDHPs, workers with documented hearing loss showed dramatic improvement (Giguère, Laroche & Vaillancourt). Another study also showed that workers who tested ELDHPs and passive hearing protectors believed they were better able to communicate and had more situational awareness when using ELDHPs (Tufts, Hamilton, Ucci & Rubas, 2011).
For some construction noise exposures, such as powder actuated nailers and pneumatic nail guns, the protection afforded by ELDHPs is especially important. High level impulsive noises have the potential to damage sensitive hearing cells. ELDHPs attenuate the impulse noises quickly enough to reduce the risk (Murphy & Byrne, 2007; Fackler, Berger, Murphy & Stergar, 2017).
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
Availability
3M
To obtain information, visit PELTOR LEP-200 and PELTOR WS LiteCom PRO III Headset
Elvex
To obtain information, visit COM-655
