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No. 534 December 2008 

QuickFit Earplug Test Device 

Objective 

To improve the level of hearing protection by providing workers with an inexpensive, easy-to-use device to check earplug fit. 

Background 

Approximately 30 million workers are exposed to hazardous 

noise on the job, placing them at risk of permanent hearing loss, 

tinnitus, and other disorders. Although the preferred solution is 

to eliminate noise through engineering controls or to reduce noise 

exposure through administrative controls, hearing protectors are 

critical when noise is unavoidable. 

Studies of hearing protector users have shown that average 

protection values in the real world are much lower than the 

labeled noise reduction ratings determined in laboratories with 

trained and motivated subjects. Even worse, many hearing protector users get virtually no protection at all because of poor fit. 

The studies also show that users have a harder time achieving 

adequate protection levels with earplugs than with earmuffs. It’s 

difficult for users to tell if earplugs are working well just by 

looking at them. A more accurate approach is to check how 

much they block or “attenuate” noise. Earplugs vary in their 

attenuation characteristics, with most providing a maximum of 

20–35 decibels of noise reduction when worn correctly. Any 

earplug that’s suitable for use in noisy settings will attenuate 

noise by at least 15 decibels. 

Personal fit testing is an effective way to help hearing 

protector users improve the fit and protection levels of the 

devices. However, existing fit-testing systems are expensive and 

unsuitable for use at many industrial worksites. 

Approach 

To offer a simpler, more affordable fit-testing device, the 

National Institute for Occupational Safety and Health (NIOSH) 

developed the QuickFit. The key innovations of the device are 

its low cost and simple operation. Low cost is achieved by using 

off-the-shelf MP3 player components (along with a few inexpensive secondary parts) and housing them in a standard earmuff shell. Simple operation was achieved by limiting the test to 

a single critical test signal and a single “go” or “no-go” 

pushbutton operation that checks for at least 15 decibels of protection. Figure 1 shows how the MP3 player and other components are configured in the QuickFit design, while Figure 2 

shows the assembled prototype. 

The QuickFit procedure is a highly simplified variation of 

the standard hearing protector evaluation specified in ANSI 

Standard S12.6. The QuickFit tests only one octave band 

centered at 1000 Hz, i.e., a digital bandpass filter was used to 

process a sample of random noise, limiting the band to the 

region from 500 Hz to 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 test signal was then 

processed to pulse at 1⁄2-second intervals. 

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USB Connector 

MP3 player On/Off/Play 

Button 

Stereo 

headphone jack 

Charger jack 

Boost Button 

Earmuff 

Housing 

Speaker 

Volume 

Status 

LED 

L R G 

Status 

LED 

Figure 1.—Diagram of components and circuits in the NIOSH 

QuickFit prototype. All components fit easily within a housing based 

on a hearing protection earmuff. 
 

 

 

 

 

 

 

 

Figure 2.—Assembled prototype of the QuickFit device. 

Figure 3.—Worker adjusting the volume control on the QuickFit 

device to set his hearing threshold before inserting an earplug. 

The QuickFit 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 just 15 decibels over the user’s hearing 

threshold. The 15-decibel boost in the QuickFit device is 

achieved by storing the test signal at two different levels in the 

left and right channels of the digital sound file. The right channel 

is recorded at a level 15 decibels higher than the left channel and 

is switched on by pressing the “boost” button. 

The device works by comparing two “threshold” tests—one 

without hearing protection and one with an earplug inserted. To 

use QuickFit, the user first turns on the device by pressing the 

power button. The device will automatically play the test sound 

(a pulsing random noise that sounds like “whooshing” to most 

people). The device is then placed over the ear to be tested, and 

the user adjusts the volume control until the sound is right on the 

edge between audible and too quiet to hear (Figure 3). That 

sound level approximates the “threshold of hearing.” Next, the 

user sets the device aside and inserts an earplug following the 

NIOSH Roll-Pull-Hold method or other technique suitable to the 

specific plug being worn (http://www.cdc.gov/niosh/mining/ 

topics/hearingloss/earplug.htm). The user then places the 

QuickFit against the protected ear while pressing the “boost” 

button. If the boosted test sound cannot be heard through the 

earplug, the user passes the test and has attained at least 

15 decibels of protection. If, however, the test sound is still 

audible through the plug, the user has failed and should refit the 

plug or try a different type, followed by a retest with the QuickFit. 

Related Developments 

A Web-based variation on the QuickFit concept is available 

online as QuickFitWeb for users who have access to a computer 

and the Internet. It uses the same test sounds as QuickFit except 

that the sounds are played through the user’s computer speakers. 

QuickFitWeb is available on the NIOSH Web site at: 

http://www.cdc.gov/niosh/mining/topics/hearingloss/quickfitweb. 

htm. The site also contains MP3 files that can be downloaded to 

a portable music player equipped with headphones to perform 

the QuickFit procedure. 

Recommendations 

Noise-induced hearing loss is 100% preventable, but once 

acquired it is permanent and life-altering. Individual fit testing of 

hearing protectors is a recommended “best practice” by the 

National Hearing Conservation Association’s Alliance Program 

with NIOSH and the Occupational Safety and Health 

Administration (see http://www.hearingconservation.org/docs/ 

AllianceRecommendationForFitTesting_Final.pdf). The QuickFit 

products are tools for workers to ensure that their hearing 

protection is actually working and preventing hearing loss. 

Manufacturers and other entities interested in disseminating the 

QuickFit technologies are encouraged to contact the NIOSH 

developers for partnership opportunities. 

For More Information 

Publications on hearing loss prevention in the mining industry 

can be downloaded from the NIOSH Mining Web site at: 

http://www.cdc.gov/niosh/mining/pubs/programareapubs14.htm. 

General information about noise and hearing loss is available at: 

http://www.cdc.gov/niosh/topics/noise. 

For more information about the QuickFit device, contact 

Robert F. Randolph, NIOSH Pittsburgh Research Laboratory, 

P.O. Box 18070, Pittsburgh, PA 15236-0070; phone (412) 386­

4660; e-mail: RRandolph@cdc.gov. You may also e-mail 

inquiries to: pithealth@cdc.gov. 

To receive NIOSH documents or for more information about 

occupational safety and health topics, contact: 1–800–CDC– 

INFO (1–800–232–4636), 1–888–232–6348 (TTY), e-mail: 

cdcinfo@cdc.gov, or visit the NIOSH Web site at http:// 

www.cdc.gov/niosh 

Mention of any company name or product does not constitute 

endorsement by the National Institute for Occupational Safety 

and Health. 

DHHS (NIOSH) Publication No. 2009–112