DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Description of

Exposure

Millions of workers at call and dispatch centers in the United States use 

headsets during most of their workday. 

They mainly include dispatchers, medical transcriptionists, air traffic control 

specialists, customer service representatives, switchboard operators, reservationists, and bill collectors. Many work 

in high-pressure, stressful environments 

with noisy surroundings and poor ergonomic conditions. [NIOSH, 1997, 

2005, 2007, 2008; Gavhed and Toomingas 2007; Patel and Broughton 2002]. 

Although these other factors can pose 

additional health risks to workers, the 

scope of this document is limited to providing recommendations for reducing 

noise hazards.

NIOSH research shows that workers at 

call and dispatch centers may face several hazards: (1) Acoustic trauma from a 

sudden spike in noise levels (e.g., from 

feedback into the headsets or a sudden change in volume) (2) background 

noise from the incoming call, and (3) 

background noise and other stressors 

in the workplace.

Background noise in the workplace (radios played by other workers, conversations, noise from heating and air conditioning systems) or from the callers’ 

locations may cause workers to turn up 

the headset volume, resulting in sudden increase in noise levels transmitted 

into their ears. Some communication 

systems may experience feedback or 

interference that could cause spikes or 

squeals from the headset. Some workers complain of fluctuations in noise 

levels in the headset or having little 

control over headset volume.

The NIOSH recommended exposure 

limit (REL) for occupational noise exposures is 85 decibels, A-weighted, as an 

8-hour time-weighted average (85 dBA 

as an 8-hr TWA). Exposures at or above 

this level are considered hazardous.

NIOSH Health Hazard 

Evaluations

NIOSH [1997, 2007] has conducted several Health Hazard Evaluations 

(HHE) on workers who wear headsets for 

most of the workday, including Federal 

Reducing Noise Hazards for Call and 

Dispatch Center Operators

Aviation Administration air traffic control specialists, emergency call center 

operators, and police station dispatchers. Figure 1 shows the typical work 

environment of a 911 call dispatch center. NIOSH has also conducted evaluations at several locations where medical transcriptionists work and at one 

fire department where emergency dispatchers work [2005, 2008]. Researchers interviewed workers, measured 

workers’ noise exposures, conducted 

area noise measurements, and measured sound levels from headsets using 

an artificial head fixture.

With the medical transcriptionists, the 

sound levels of the transcription recordings often varied even within a 

single dictation, forcing the transcriptionists to manually adjust the volume 

higher or lower. In some instances, the 

transcriptionists adjusted the volume 

to a higher or maximum setting to hear 

a low or quiet dictation, then the dictation levels or background noise spiked 

suddenly and was transmitted into 

their ears at those maximum levels. Researchers found that sound levels and 

high-frequency tones played at maximum volume resulted in equivalent 

sound levels under the headsets that 

were 4–18 dBA higher than the NIOSH 

recommended limit of 85 dBA. Thirteen of 21 transcriptionists (62%) interviewed reported having problems with 

Summary

Workers at call and dispatch centers may suffer health risks associated with high noise levels from 

their headsets. The National Institute for Occupational Safety and 

Health (NIOSH) has developed 

recommendations for prevention.
the fluctuation in sound levels from the transcription communication equipment and headsets [NIOSH 2005]. 

As for the 911 Fire Department dispatchers, background 

noise in the work area did not exceed the NIOSH REL (The 

median value of overall full-shift noise levels was 60 dBA). 

However, noise from loud alarms, visitors, and other distractions did cause the dispatchers to increase the volume 

on their headsets to mask the noisy environment. Although 

an examination of actual 911 recordings played through 

the headsets produced peak levels as high as 100 dB SPL at 

maximum volume, a review of the dispatchers’ audiograms 

showed no evidence of noise-induced hearing loss. However, repeated and prolonged exposure to such levels can 

cause hearing loss and ringing in the ear [NIOSH 2008].

Laboratory research on the communication headsets used 

in the HHEs showed that if the volume controls of the 

headset and associated communication equipment were 

placed in the middle position or lower, the noise exposures 

through the headsets would be at a safe level for an 8-hour 

workshift [NIOSH 1997, 2005, 2007, 2008]. Figure 2 shows 

the laboratory testing of the various communication headsets and equipment using an acoustic head fixture.

Overall, the NIOSH evaluations did not reveal hearing 

loss problems among call center operators and dispatchers that can be directly attributed to noise exposures from 

their headsets or the surrounding environment. However, most workers interviewed reported various symptoms 

often associated with prolonged exposure to high noise 

levels. Symptoms included ringing in their ears, headaches, 

irritability, increased tension, and fatigue. 

Other Studies

Research by the United Kingdom’s Health and Safety Executive examined noise exposures of 150 call center employees. 

Background noise levels were measured to be 62 ± 2 dBA. 

Individual noise levels generated by the headsets did not exceed 84 dBA while the mean daily noise exposures ranged 

from 68–77 dBA [Patel and Broughton 2002].

Researchers in Australia have examined 123 incidents of 

acoustic shock among 103 call center operators. Acoustic 

shock is described as a sudden and unexpected increase in 

noise levels transmitted through the headsets into the operator ears. Operators described being shocked by the incidents 

and experienced a range of symptoms including pain in the 

ear (81%), tinnitus (ringing in the ears) (50%), vestibular 

(balance) disturbance (48%) and hyperacusis (sensitivity to 

noise) (38%). Although hearing loss was not a commonly reported symptom (18%), hearing tests showed atypical hearing loss patterns [Westcott 2006].

A survey of 1,183 call center operators in Sweden found unsatisfactory conditions at many workstations, including high 

noise levels. Seventy-four percent of the operators reported 

dissatisfaction with their work environments and the background noise levels. The highest sound level known to not 

disturb speech comprehension, 55 dBA, was exceeded at 

72% of the workstations studied. The most common noise 

sources reported were other operators’ voices and the ventilation system [Gavhed and Toomingas 2007].

Recommendations

NIOSH recommends that workers and employers at call centers take the following steps to protect against hearing damage and other adverse health effects:

Workers

 Notify your supervisor and take protective action if you 

experience tinnitus (ringing in the ears), a dulled sense of 

hearing, or a fullness in the ears after a workshift or exposure to noise (that was not present before the exposure or 

workshift). This indicates an overexposure that, if repeated, will likely cause permanent effects.

 Do not set the volume control above the middle point. 

The lower the better.

 Ask to try different headsets with improved protection or 

noise-cancelling features.

 Clean and maintain your headset periodically. Replace 

them when you notice damage or decreased performance.

 Take advantage of breaks (in quiet areas) whenever 

possible.

Figure 1. New York Police Department 911 dispatch center 

with an open floor plan and crowded work environment
Figure 2. Laboratory testing using the KEMAR acuoutic head 

fixture

NIOSH [1997]. NIOSH Health Hazard Evaluation Report, 

Federal Aviation Administration, Bradley Airfield Windsor Locks, CT. By Tubbs R, Franks J. Cincinnati, OH: U.S. 

Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health. NIOSH HETA Report No. 

96−0814−2663 [http://www.cdc.gov/niosh/hhe/reports/

pdfs/1996-0184-2663.pdf]. 

NIOSH [1998]. Occupational noise exposure. Cincinnati, OH: 

U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 

No. 98–126 [http://www.cdc.gov/niosh/docs/98-126/]. 

NIOSH [2005]. NIOSH Health Hazard Evaluation Report, 

Kaiser Permanente, California. By Tubbs R, Kardous C. 

Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, 

National Institute for Occupational Safety and Health. 

NIOSH HETA Report Nos. 2003−0273, 2003−0280, 

2003−0287−2974 [http://www.cdc.gov/niosh/hhe/reports/

pdfs/2003-0273-2974.pdf ].

NIOSH [2007]. NIOSH Health hazard evaluation report, 

New York City Police Department, Police Communications Section, New York. By Driscoll R, Tubbs R, Habes 

D. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 

National Institute for Occupational Safety and Health. 

NIOSH HETA Report No. 1997−0137−3026 [http://www.

cdc.gov/niosh/hhe/reports/pdfs/1997-0137-3026.pdf].

NIOSH [2008]. Evaluation of potential noise hazards to mechanics and 911 dispatchers at a fire department, Anchorage, AK. By Achutan C, Kardous C. Cincinnati, OH: U.S. 

Department of Health and Human Services, Centers for 

 Communicate with your supervisor when noise levels are 

high and ask co-workers to use low volume on soundgenerating devices.

Employers

 Consider supplying communication systems with noiselimiting features. 

 Install noise controls to reduce background noise levels 

in the work environment, such as barriers between workstations or sound-absorbing materials on hard surfaces 

in the room [NIOSH 2008].

 Provide workers with a variety of communication headsets that offer adjustable volume controls, noise-limiting 

or cancelling features, and improved comfort and protection from ambient noise. 

 Establish a regular training program and educate workers 

about the proper use of headsets, communication equipment, and maintaining a quiet workplace environment. 

 Evaluate workplace exposure for noise levels above the 

NIOSH REL of 85 dBA and establish a hearing conservation program for exposed workers, including yearly hearing tests. The NIOSH Criteria Document on Occupational Noise Exposure (http://www.cdc.gov/niosh/

docs/98-126/) provides useful information about implementing a program to prevent hearing loss. In addition, the basic elements of a hearing conservation program must meet the requirements of the Occupational 

Safety and Health Administration (OSHA) hearing conservation amendment [29 CFR*

 1910.95]. Specific guidelines on implementing effective hearing conservation 

programs can be found at http://www.osha.gov/dts/osta/

otm/noise/hcp/index.html

Acknowledgements

This document was prepared by Chucri Kardous and Susan Afanuh of NIOSH. It was based on research by Randy Tubbs†

, Chandran Achutan†, Chucri Kardous, Richard 

Driscoll, Daniel Habes†, and John Franks†.

References

BLS [2009] Occupational outlook handbook, 2010−2011. 

Washington, DC: Bureau of Labor Statistics [http://www.

bls.gov/oco/ocos280.htm]. 

CFR. Code of Federal regulations. Washington, DC: U.S. 

Government Printing Office, Office of the Federal Register.

Gavhed D, Toomingas A [2007]. Observed physical working 

conditions in a sample of call centres in Sweden and their 

relations to directives, recommendations and operators’ 

comfort and symptoms. Int J Ind Ergonomics 37:790−800.

* Code of Federal Regulations. See CFR in References

†Formerly with NIOSH References
This document is in the public domain and may be 

freely copied or reprinted. NIOSH encourages all 

readers of the Workplace Solutions to make them 

available to all interested employers and workers.

As part of the Centers for Disease Control and Prevention, 

NIOSH is the Federal agency responsible for conducting research and making recommendations to prevent work-related 

illness and injuries. All Workplace Solutions are based on research studies that show how worker exposures to hazardous 

agents or activities can be significantly reduced.

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

4676 Columbia Parkway

Cincinnati, OH 45226–1998

Official Business

Penalty for Private Use $300

Safer • Healthier • PeopleTM

For More Information

For more information about hearing loss prevention or 

stress, visit the NIOSH Web site: 

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

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

To obtain information about other occupational safety and 

health topics, contact NIOSH at 

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348 ■ E-mail: cdcinfo@cdc.gov

or visit the NIOSH Web site at www.cdc.gov/niosh

For a monthly update on news at NIOSH, subscribe to 

NIOSH eNews by visiting www.cdc.gov/niosh/eNews

September 2011

Disease Control and Prevention, National Institute for Occupational Safety and Health. NIOSH HETA Report No. 

2007−0235−3064 [http://www.cdc.gov/niosh/hhe/reports/

pdfs/2007-0235-3064.pdf ].

Patel J, Broughton K [2002]. Assessment of the Noise Exposures of Call Centre Operators. Ann Occup Hyg 46:653−661.

Westcott M [2006]. Acoustic shock injury (ASI). Acta OtoLaryngologica 126:54−68

Reducing Noise Hazards to Call and Dispatch Center 

Operators

DHHS (NIOSH) Publication No. 2011-210