Are your ears really protected? Find out with NIOSH's QuickFitWeb
Approximately 30 million workers are exposed to hazardous noise on the job. While we would prefer to eliminate noise through engineering controls or reduce exposure to noise through administrative controls, hearing protectors are critical when noise is unavoidable.
Hearing protectors only work if they fit your ears and you wear them properly. An earplug that doesn't quite fill your ear canal or an earmuff with a small crack in the padding will let lots of noise into the ears through any gaps, even tiny ones.
QuickFitWeb
Hearing Protection Quick Test
Instructions
- For best results, conduct this test in a quiet room (background noises can interfere with the test sounds). You can listen through speakers or headphones connected to your computer. Speakers will work with either earmuffs or earplugs. Headphones can be used with earplugs and should be the full-sized "circumaural" type that covers the entire ear and does not press on the inserted earplug.
- Click "1. Without hearing protection" in the sound player display above and adjust the volume so the sound is barely audible. (You may need to use the controls on your computer along with the on-screen slider.)
- Put on your hearing protection. If using soft foam earplugs, we recommend the NIOSH Roll-Pull-Hold method.
- Click "2. With hearing protection" and listen for the test sound. You should not be able to hear the test sound if your hearing protection is fitted properly. If you can hear this track, re-fit your hearing protection and repeat this step.
To help you get the most from your hearing protectors, researchers at the National Institute for Occupational Safety and Health's (NIOSH) Pittsburgh Research Laboratory developed QuickFitWeb, an online tool to check your hearing protection in a minute or less.
Poor Fit = Poor Protection
Studies of hearing protector users have shown repeatedly that average protection values in the real world are much lower than the labeled Noise Reduction Ratings (NRR) determined in laboratories with trained and motivated subjects. Even worse, many hearing protector users get virtually no protection at all because of poor fit. It's hard to tell if your hearing protectors are working well just by looking at them. A more accurate approach is to check how much they block or "attenuate" noise. Hearing protectors vary in their attenuation characteristics, with most providing a maximum of 20 to 35 decibels of noise reduction when worn correctly. Any hearing protector that's suitable for use in noisy settings will attenuate noise by at least 15 decibels.
How QuickFitWeb Checks Hearing Protectors
The NIOSH QuickFitWeb helps you determine if your hearing protection is giving you at least 15 decibels of attenuation by comparing two "threshold" tests—one without hearing protection and one with the devices on or in your ears. To use QuickFitWeb, play the test sound (a pulsing random noise that sounds like "wooshing" to most people) from the website. As you listen to the sound, adjust the volume on your computer until the sound is right on the edge between audible and too quiet to hear. That sound level is your "threshold of hearing." Then put on your hearing protectors and play the next test sound. The second sound is exactly the same as the first except that it's 15 decibels louder. If you can hear the louder sound through your hearing protection, the devices are attenuating sound by less than 15 decibels and are not protecting you adequately. You need to correct the problem by trying hearing protectors that fit you better or correcting the way you put them on. Then you can try the test again until you get a good fit.
Under the Hood
The QuickFitWeb is a highly simplified variation of standard hearing protector evaluations. The QuickFitWeb tests only one octave band centered at 1000 Hz. That is, we filtered a sample of random noise to have maximum energy at 1000 Hz and with energy dropping to zero at 500 Hz and 2000 Hz. Using just a single test frequency saves time and serves the purpose of checking for adequate fit since well-fit hearing protectors will have good attenuation on all frequencies. The QuickFitWeb also streamlines testing by checking for just one attenuation value: 15 decibels. If a protector is poorly fitted, it will usually provide far less than 15 decibels of attenuation. Protectors suitable for noisy environments are generally rated to provide at least 20 decibels of attenuation so they should completely block a sound that's just 15 decibels over the user's hearing threshold.
Related Developments
QuickFitWeb is a spinoff from the NIOSH QuickFit standalone device. QuickFit is a small, self-contained device that looks like one side of a set of earmuffs and allows the user to play test sounds, adjust the threshold,and check for at least 15 decibels of protection. It was designed to use inexpensive off-the-shelf circuits and parts so that it could be produced at very low cost. Ideally, it could be placed affordably near any noisy worksite so workers could check their earplugs every time they put them in. Prototypes of the QuickFit device started a series of field evaluations in February 2008.
Another related product is QuickFitMP3—a set of digital sound files in the popular MP3 format that can be played on almost any computer or music player. By playing the sounds in sequence, users can test whether their hearing protectors are attenuating noise by at least 15 decibels. These MP3 files are downloadable now from the QuickFitWeb page. A future enhancement of this approach will be to provide a sequence of MP3 "tracks" that vary by 5 decibels to allow users to assess approximately how much attenuation they are getting from their hearing protectors. They will also use the separation possible with stereo headphones to permit testing earplugs inserted in right versus left ears independently. These added sound files will allow some additional training and evaluation scenarios that are beyond the scope of the current QuickFit products.
Noise-induced hearing loss is 100 percent preventable but once acquired it is permanent and life-altering. The QuickFit products are tool for workers to ensure that their hearing protection is actually working and preventing hearing loss.
—Robert F. Randolph, M.S.
The author is the Manager of the Hearing Interventions Team at NIOSH's Pittsburgh Research Laboratory
More information on work-related hearing loss is available on the Noise and Hearing Loss Prevention page on the NIOSH website.
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Comments
Maybe I missed it, but I didn't see any recommendations regarding left right handedness. I for instance know that I hear better in one ear then the other. This may not be a factor when testing with headphones but could affect the outcome in other instances. In all though I think it is an invaluable tool
Posted 5/15/08 at 4:06 pm
You're not alone—many people have better hearing on one side, which can complicate testing hearing protector fit. When asymmetrical hearing ability is combined with a loudspeaker fit testing setup, the results will primarily reflect protection levels for the "better" ear. That's because the "worse" ear won't hear the test sounds as well. Ideally, each ear should be tested independently from the other, but that may be virtually impossible when listening to diffuse sound through loudspeakers. If you know or suspect that your ears have different sensitivities to sound, we recommend that you use a good set of around-the-ear headphones to perform the test. To test each ear independently with headphones, use the balance control on your system to send all of the sound to one side at a time. If you want to stick with loudspeakers, you can still isolate the ears somewhat. To do this, we suggest testing your "better" ear first. After you do the test once with your best ear, isolate that ear from sound by inserting an earplug into it, and consider putting one side of an earmuff over it to get even more isolation. Then, you can go ahead with a test of the "worse" ear.
The instructions don't yet specifically address the situation of asymmetrical hearing ability coupled with loudspeaker testing because we were trying to keep the procedure as quick and simple as possible. However, the situation is very plausible and some users could benefit from information on recommended ways to test each ear separately. We'll incorporate this excellent suggestion into the the process of updating and improving QuickFitWeb.
Posted 5/16/08 at 3:10 pm
Can the computer make a difference? I've tried this with 3 different types of plugs and even though I believe that I have a good fit, I still hear the "with hearing protection" sound. I've been using hearing protection and instructing others on proper selection, insertion and fit for 32 years, so I'm pretty confident that I have a good fit.
Posted 5/20/08 at 10:36 pm
The computer used for QuickFitWeb can certainly make a difference under some conditions, although we have tried to minimize the number of things that can go wrong. To confirm the validity of QuickFitWeb's test sounds, we've measured its output through several typical headphones and speakers connected to different desktop and laptop computers. However, it's not feasible for us to test every possible combination of computers, sound systems, and software. In your case, I would look first at the overall volume level on your computer. QuickFitWeb works best when the quietest "threshold" sound you can hear occurs when its volume control slider is somewhere near the center. You probably have software volume controls on your computer and possibly also on your speakers or headphones. Try adjusting the system and speaker volume controls until the QuickFitWeb sound is just barely audible when its slider is in the middle. Then, use the QuickFitWeb volume slider control to find your threshold of hearing. If you are using loudspeakers, you may also want to switch to headphones for the test to minimize the effects of background noise. A less likely possibility is that a driver or other software component is performing compression or automatic volume adjustments that are interfering with QuickFitWeb. If you still seem to be getting unexpected results, I will be happy to correspond with you offline about your specific setup.
Posted 5/21/08 at 11:10 am
Interesting approach for those with regular internet access—likely not suitable for people with any significant amount of hearing loss, since getting enough gain from the unoccluded series could be tough. The assumption of 15 dB as a sufficient protected level could be problematic as well—I just did a project at a metal can plant where exposures of 100 to 105 were pretty common. It could be an issue of this test indicating a worker is sufficiently protected when in fact they are not. Of course, there is the fundamental question of objective vs subjective approaches—the threshold setting/threshold response issue can be difficult to address. Having this technology in a hand-held could be a good idea, as it simplifies delivery.
Posted 5/20/08 at 10:54 pm
Mr. Hager raises some good points that will help clarify the uses and limitations of QuickFit and QuickFitWeb. Our design objective was to give hearing protector users a way to check the fit as quickly and simply as possible. While simplification sometimes forced us to make hard decisions about which capabilities to keep and which to eliminate, we tried to preserve as much everyday usefulness for as many users as we could. For instance, as Mr. Hager points out, users who have a significant hearing loss may have difficulty adjusting the QuickFit loud enough to reach their hearing threshold. Our goal with the standalone QuickFit is to reach hearing thresholds of 60-65 decibels (dB) at 1000 Hz, which should accommodate most users—even those with substantial noise-induced hearing loss in the 4000-6000 Hz range. Those users who have hearing that approaches or exceeds the limits of QuickFit would probably benefit from an individualized consultation with an audiologist or physician.
QuickFit relies on a subjective Real-Ear Attenuation at Threshold (REAT) technique because it is simpler than an objective Microphone In Real Ear (MIRE) technique. Moreover, REAT doesn't require special earplugs or in-ear microphones. On the other hand, MIRE can be more accurate and reliable than REAT, so periodic MIRE fit assessments could be used to complement more frequent checks with QuickFit.
Our choice of a 15 dB attenuation value also deserves some clarification. We wanted to test just one attenuation level because it takes much less time than testing a range of attenuation levels. We picked 15 dB because all users of standard hearing protectors should get more than 15 dB of protection (excluding some musicians and other specialties where sometimes 10 dB or so is ideal). How much more than 15 dB is ideal for a particular individual depends on their noise environment and what sounds they still need to hear "through" their hearing protectors. QuickFit is intended to "catch" poorly fitted hearing protectors, but we agree that a more extensive assessment is appropriate for individuals who need an especially high degree of protection because they are exposed to extremely high noise levels or for other safety considerations.
QuickFit can never replace or eliminate personal attention from hearing professionals using more sophisticated fit testing systems. However, as Mr. Hager points out, it can be used to simplify delivery of fit testing so that it is more readily available when and where protection is needed most.
Posted 5/29/08 at 3:45 pm
I am a graduate student at Old Dominion University and I am also an active duty Navy Chief Hospital Corpsman with extensive background in hearing loss prevention. I think that this device would be an invaluable asset when fitting members for hearing protection. I have found that when fitting members for hearing protection it is mostly for comfort and that does not correlate to good protection all the time. Have there been any epidemiological studies that show the advantages of using this device in addition to the normal comfort fit. How many organizations do you know that are using this product on a consistent basis to ensure proper protections? Have there been any studies to examine end users who were fitted for hearing protection using the comfort-size fitting method alone and then re-fitted using this device to see if there was any need to change protection size or type. It is also import for use to emphasize how quickly noise can produce a threshold shift and this device and also be used to show the end user how much noise the protection in preventing, and that might help them to wear their protection.
Posted 10/19/08 at 4:10 pm
I agree that it's important to have evidence supporting the benefits and acceptance of the QuickFit technologies.
A number of studies have shown that the general approach of individual fit testing for hearing protectors is an effective technique for improving hearing protector attenuation. These findings have prompted the National Hearing Conservation Association's NHCA-OSHA-NIOSH Alliance to endorse individual fit testing as a "best practice." QuickFitWeb and the QuickFit device incorporate key aspects of the recommended individual fit testing techniques, so we expect them to show similar benefits. We have completed acoustic testing of the NIOSH technologies, but we are just beginning the process of conducting tests of attenuation levels with potential users. We are looking for partner organizations to assist us with access to field sites and workers who can help us evaluate the performance of the QuickFit technologies.
The QuickFit is brand new and not yet in production, so it's not yet in widespread use in organizations. We are actively looking for development and manufacturing partners to take the technology and produce it in large quantities. As that happens, we plan to track dissemination and use of the device.
Further evaluation testing and dissemination are activities scheduled in a NIOSH Pittsburgh Research Laboratory project for the coming year. As soon as these activities are completed, the results will be published and made available on the NIOSH website.
You make a good final point about training users about preventing temporary threshold shifts (TTS) through use of hearing protection. We will be sure to include information about the TTS danger signs in the training materials we are preparing to support QuickFit users.
Posted 5/29/08 at 3:45 pm