Reducing Noise Exposure

Image of sound meter and tractor trailer truck.

HPD Well-Fit™ – new page – not yet cleared

The NIOSH Recommended Exposure Limit (REL) for occupational exposure is 85 decibels (dB), A-weighted, as an 8-hour time-weighted average with a 3 dB exchange rate (i.e. for every increase of 3 dB, the recommended exposure time will be cut in half), and any exposure above 140 dB is not permitted. Exposures at and above 85 dB are considered hazardous and controls should be put in place to reduce their effects. The Occupational Safety and Health Administration (OSHA) requires that workers use Hearing Protection Devices (HPDs) to protect themselves from the damaging effects of noise when noise levels cannot be reduced through engineering controls.

An estimated 22 million workers in the US are exposed to hazardous noise each year and as many as 10 million US workers have occupational hearing loss. Noise-Induced Hearing Loss (NIHL) is the most common occupational injury in the US and although it is permanent and irreversible, it is 100% preventable.

As administrators implement hearing conservation programs, it is important to test the validity of such programs. The best way to do this is to test the HPDs that workers use every day. Every HPD sold in the US is evaluated in a laboratory and labeled with a Noise Reduction Rating (NRR) that determines how much noise is attenuated for each HPD. Research, however, has shown that most workers achieve less than half of the sound attenuation predicted by the NRR.

What is fit-testing?

Fit-testing measures the noise reduction an HPD provides for an individual worker and calculates that worker’s Personal Attenuation Rating (PAR), thereby identifying those at risk for developing hearing loss due to poor earplug fit. Fit-testing helps to achieve a better fit of HPDs to increase hearing protection in workers.

There are two ways of fit-testing: proactive and reactive testing. With proactive testing, HPDs are tested before any issues arise, typically along with annual hearing tests. Reactive testing, on the other hand, occurs only when hearing loss or other HPD-related concerns have developed. Ideally, every worker would be fit-tested annually and changes to the HPDs would occur as needed (e.g. if a worker is fit-tested with a certain set of earplugs and there is not sufficient noise reduction, a different type will be fit-tested and used). Unfortunately, this doesn’t usually happen, so the NIOSH Hearing Loss Prevention Team developed HPD Well-Fit™ to address several issues with other fit-check systems such as cost, the time consuming nature of the test, and the need for extra equipment.

HPD Well-Fit™ requires only a computer running the Windows 7 operating system or above with a high-definition sound card, a mouse with a scroll wheel, and sound-isolating headphones. It can be used to test any type/brand of earplug and provides results within 7 to 10 minutes, including training. HPD Well-Fit™ can test the noise reduction of any earplug and is inexpensive, fast, and portable.

Why is it important to fit-test HPDs?

Fit-testing is an effective, practical, and essential tool for preventing occupational hearing loss. When noise levels cannot be reduced though engineering controls, OSHA requires that workers use HPDs to protect themselves from the damaging effects of noise. Despite decades of OSHA-mandated HPD use, NIHL remains highly prevalent.

It is important to fit-test HPDs because:

  • Failure to properly fit and wear hearing protectors has been cited as the leading cause of occupational hearing loss
  • Less than 5% of workers actually achieve the level of protection predicted by the NRR
  • It is important to maintain an appropriate HPD inventory, and fit-testing can reveal the need for different hearing protectors in the workplace
  • It can demonstrate a worker’s proficiency in fitting his or her protection, possibly indicating the need for more training
  • Individual fit-testing is the only means to determine how well a protector will perform with an individual
  • All ears are not the same (ear canal size and shape differ between workers), therefore there is a need to better identify those at risk for hearing loss
  • It is important to avoid over-protection and under-protection. Over-protection may cause workers to frequently remove HPDs in order to hear quieter
  • conversation, exposing them to hazardous noise, and under-protection leaves workers vulnerable at all times when hazardous noise is present
  • Many workers believe that there is nothing they can do to protect their hearing by themselves, and fit-testing will change this and increase self-efficacy
  • Fit-testing HPDs will help cut costs in the long run (e.g. costs due to a Standard Threshold Shift (STS) and workers’ compensation claims)
  • It is a valuable tool for documenting if workers are receiving adequate protection
  • Fit-testing is a “best practice” for protecting workers’ hearing

Related Links

NIOSH Science Blog: NIOSH HPD Well-Fit™: The Future is Fit-Testing

Measuring How Well Earplugs Work
DHHS (NIOSH) Publication No. 2015-181 (May 2015)

HPD Wellfit Fast and Accurate Fit Testing
DHHS (NIOSH) Publication No. 2012-179 (October 2012)

NIOSH Science Blog: QuickFitWeb

Page last reviewed: February 6, 2018