In an Australian clinical series of acoustic shock injury, 95% of 103 call centre operators reported pain after a headset acoustic incident, and 50% reported tinnitus (Westcott, Acta Oto-Laryngologica 2006). The paradox is that the same workforce rarely reaches a hazardous daily noise dose: 78 operators measured over their shifts averaged 74.7 dBA, below the 80 dB(A) EU lower action value (Pawlaczyk-Łuszczyńska et al., Noise and Health 2018). Medico-legal files show the same split: 90% of 30 cases had tinnitus, yet 43% had normal audiometry (Parker et al., International Journal of Audiology 2014), and the US alone employs 2,595,750 customer service representatives (BLS OEWS May 2025). Acoustic shock is one of the less visible strains in a job already known for the pressures covered in our call center agent burnout and turnover statistics. We aggregated data from Acta Oto-Laryngologica, AudiologyOnline, Noise and Health, the International Journal of Occupational Medicine and Environmental Health, the UK Health and Safety Executive, NIOSH, EU and US noise regulations, the US Bureau of Labor Statistics, and a set of medico-legal case series.
TL;DR
- 103 Australian operators were exposed to 123 acoustic incidents between 1994 and 1999 (Westcott, Acta Oto-Laryngologica 2006).
- 22% of 90 operators at one Danish call centre had experienced an acoustic shock (Hinke and Brask 1999, via AudiologyOnline 2002).
- 4 of 12 communication headsets exceeded 85 dB at full volume (Kozlowski, IJERPH 2022).
- 0 acoustic shocks were recorded among 39 dispatchers monitored over shifts of up to 12 hours (Venet et al., Int J Occup Med Environ Health 2018).
- 90% of 30 medico-legal cases had tinnitus, yet 43% had normal audiometry (Parker et al., International Journal of Audiology 2014).
- 43.8% of interviewed call center operators diagnosed with an occupational disease were later dismissed (Altundaş Hatman and Torun, Med Lav 2022).
- Triggering sounds: 2.3 to 3.4 kHz at 82 to 120 dB SPL at the eardrum (Milhinch, AudiologyOnline 2002).
- UK headset limiters block noise above 118 dB, standard since 1991 (HSE, Acoustic shock guidance).
- Mean daily headset dose of 74.7 dBA across 78 operators (Pawlaczyk-Łuszczyńska et al., Noise and Health 2018).
- Only 1.4% of 177 operators exceeded an 85 dB daily dose (Pawlaczyk-Łuszczyńska et al., Int J Occup Med Environ Health 2022).
- 2,595,750 US customer service representatives in May 2025 (BLS Occupational Employment and Wage Statistics).
1. How Often Acoustic Incidents Happen
There is no national acoustic shock registry, so incidence has to be pieced together from clinical case series and single-site surveys. The Australian clinical cases in the table below came from a population of 16,000 call centre workers across four states. Dividing the two gives 103 / 16,000 = about 0.6%, but that is a floor rather than a rate, because only incidents that cost working time and reached an audiologist were counted.
Single-site surveys that ask operators directly land far higher. 22% of 90 operators at one Danish call centre had experienced an acoustic shock (Hinke and Brask 1999, via AudiologyOnline 2002), and a Trends in Hearing 2018 review cites an estimate that acoustic shock affects nearly 13% of call center workers (John et al. 2015). The gap between a clinical floor and a survey ceiling is the real story: most incidents never become a medical record.
| Metric | Value | Source |
|---|---|---|
| Australian clinical series | 103 operators, 123 acoustic incidents, 1994 to 1999, from a population of 16,000 workers | Westcott, Acta Oto-Laryngologica 2006 |
| Operators with repeated incidents | 20 (19%), from 1 to 9 incidents, mean 1.64 per person | Milhinch, AudiologyOnline 2002 |
| Danish call centre, operators who had an acoustic shock | 22% of 90 | Hinke and Brask 1999, via AudiologyOnline 2002 |
| Estimated share of call center workers affected | Nearly 13% | John et al. 2015, cited in Trends in Hearing 2018 |
| Dispatch centre shifts of up to 12 hours, acoustic shocks recorded | 0 among 39 operators in three centres | Venet et al., Int J Occup Med Environ Health 2018 |
Context note: across the 14 Danish call centres studied, some sites had recorded no incidents at all (Milhinch, AudiologyOnline 2002), and the dispatch-centre study saw none during monitored shifts. Incidence clusters by site, equipment and line quality rather than spreading evenly. Most recent available data: the 2018 dispatch-centre study and the 2018 Trends in Hearing review.
2. Symptoms: Pain, Tinnitus, Hyperacusis and Balance
Acoustic shock is defined by its symptom cluster, not by measurable damage. Pain was reported by 95% of the 103 Australian cases and tinnitus by 50%, with hyperacusis in 32% (Westcott, Acta Oto-Laryngologica 2006). Westcott singles out hyperacusis as the most distressing and durable symptom, which matters for return-to-work: an agent who cannot tolerate a headset cannot do the job. Readers following the sound-tolerance side of this can see our hyperacusis and sound tolerance therapy statistics.
Ear pain dominates the pain reports, and balance problems are almost as common as tinnitus, which is why a hearing test alone says little about the injury. Measured hearing loss, by contrast, is the minority finding (see section 3).
| Metric | Value | Source |
|---|---|---|
| Any pain / tinnitus after an incident (clinical series of 103) | 95% / 50% | Westcott, Acta Oto-Laryngologica 2006 |
| Hyperacusis (clinical series) | 32% | Westcott, Acta Oto-Laryngologica 2006 |
| Ear pain specifically | 81% | Milhinch, AudiologyOnline 2002 |
| Vestibular disturbance (loss of balance) | 48% | Milhinch, AudiologyOnline 2002 |
Outlier note: symptoms stack. The Australian cases averaged 2.7 symptoms per shock, with some operators reporting seven or eight (Milhinch, AudiologyOnline 2002), and McFerran’s review places the mean at 2.7 to 3.2 symptoms per patient across studies, adding that some workers go on to develop anxiety, insomnia and post-traumatic stress disorder (McFerran, Canadian Audiologist 2015). Most recent available data: 2006 clinical series and 2015 review.
3. Claims, Court Cases and Medico-Legal Profiles
Acoustic shock reached medicine largely through litigation, and the medico-legal case series show why claims are hard to win. Among 30 medico-legal cases, 90% had tinnitus but 93% had a normal ear examination and 43% had normal audiometry (Parker et al., International Journal of Audiology 2014). The same series found psychopathology in 63% and previous ear pathology in 70%, the kind of finding that makes causation hard to establish in court.
Payouts on record are small. In Woodings and Others v British Telecommunications plc (2003), five claimants alleging earache, auditory interference and vertigo settled for sums between GBP 500 and GBP 750 (Solicitors Journal 2007). The long tail shows up in employment outcomes instead: among call center operators diagnosed with an occupational disease, 43.8% of those interviewed were dismissed afterwards (Altundaş Hatman and Torun, Med Lav 2022).
| Metric | Value | Source |
|---|---|---|
| Medico-legal acoustic shock cases reviewed | 30 (60% female, mean age 41.6) | Parker et al., Int J Audiol 2014 |
| Cases with tinnitus / psychopathology | 90% / 63% | Parker et al., Int J Audiol 2014 |
| Normal examination / normal audiometry | 93% / 43% | Parker et al., Int J Audiol 2014 |
| UK compensation claimants reviewed | 18 (16 female, 2 male) | Lawton, Proceedings of the Institute of Acoustics 2003 |
| Claimants alleging hearing loss / tinnitus heard straight after the incident | 14 of 18 / 11 of 18 | Lawton, Proceedings of the Institute of Acoustics 2003 |
| Woodings v BT (2003) settlement per claimant | GBP 500 to GBP 750, five claimants | Solicitors Journal 2007 |
| Call center operators with a confirmed occupational disease (2007 to 2018 records) | 122 of 173 (70.5%), hearing loss 12.5% of diagnoses | Altundaş Hatman and Torun, Med Lav 2022 |
| Diagnosed operators dismissed / who quit afterwards | 43.8% / 18.7% (of 64 interviewed) | Altundaş Hatman and Torun, Med Lav 2022 |
Context note: two of Lawton’s 18 claimants were judged to have catastrophic tinnitus (Lawton, Proceedings of the Institute of Acoustics 2003). We found no public, aggregated compensation statistics for acoustic shock in UK, US or Australian claims data, so these case series are the most recent available data.
4. Anatomy of an Acoustic Incident: Frequency, Level and Limiters
The acoustic profile explains both the injury and why limiters only partly solve it. The incidents behind the Australian cases sat at 2.3 to 3.4 kHz and 82 to 120 dB SPL at the eardrum, a narrow, high-pitched band. Rise times of 0 to 20 ms (McFerran, Canadian Audiologist 2015) mean the sound peaks before an operator can pull the headset off.
Limiters cap the ceiling, not the startle. The HSE acoustic shock guidance says UK headset limiters stop any noise above 118 dB, but the Australian incidents started as low as 82 dB, well under that cap. Lawton calculated that 118 dB at the ear is equivalent to an unobstructed field of 105 to 111 dB(A), and that a typical exposure lasts 5 to 15 seconds before the headset comes off (Lawton, Proceedings of the Institute of Acoustics 2003).
| Metric | Value | Source |
|---|---|---|
| Frequency / intensity at the tympanic membrane | 2.3 to 3.4 kHz / 82 to 120 dB SPL | Milhinch, AudiologyOnline 2002 |
| Rise time of acoustic incidents | 0 to 20 ms | McFerran, Canadian Audiologist 2015 |
| Single-exposure level usually linked to acoustic trauma | Typically greater than 120 dB | McFerran, Canadian Audiologist 2015 |
| Danish sound bursts | 56 to 108 dB SPL, 100 Hz to 3.8 kHz | Hinke and Brask 1999, via AudiologyOnline 2002 |
| UK headset limiter ceiling | 118 dB | HSE, Acoustic shock guidance |
| Year limiters became standard in major headsets | 1991 (DTI specification 85/013) | HSE, Acoustic shock guidance |
| Free-field equivalent of the 118 dB limit | 105 to 111 dB(A) | Lawton, Proceedings of the Institute of Acoustics 2003 |
| Typical exposure before headset removal | 5 to 15 seconds | Lawton, Proceedings of the Institute of Acoustics 2003 |
Context note: the international reference for terminal-side limiting is ITU-T Recommendation P.360, whose 07/2006 edition is in force and sets limits on the acoustic pressure that handset and headset earphones may generate (ITU-T P.360 summary). The 2006 journal write-up of the same Australian cases gives the trigger range as 82 to 110 dB SPL rather than 82 to 120, see the Data watch note in the Methodology section.
5. Daily Headset Doses of Agents
Dose and shock are two different hazards. Measured over a shift, agents rarely reach the levels associated with noise-induced hearing loss: 78 operators averaged a daily exposure of 74.7 dBA, ranging from 68 to 79 dBA (Pawlaczyk-Łuszczyńska et al., Noise and Health 2018). The UK benchmark study of 150 operators found mean daily exposures of 68 to 77 dBA, with headset levels never above 84 dBA (Patel and Broughton, Annals of Occupational Hygiene 2002, as summarized by NIOSH 2011).
The averages hide the volume knob. In the 78-operator study, 77.6% set their headset above half of maximum and 14.9% ran it at 100%, and the level under the headset reached up to 88 dBA. Self-reported tinnitus after work and hyperacusis were present even though no daily dose in that cohort crossed 80 dBA. For how such doses are measured in the field, see our sound level meter and occupational monitoring statistics.
| Metric | Value | Source |
|---|---|---|
| Mean daily exposure, 78 operators | 74.7 ± 2.5 dBA (68 to 79 dBA), with 5.2 ± 2.0 h on calls per day | Pawlaczyk-Łuszczyńska et al., Noise and Health 2018 |
| Headset volume above 50% / at 100% | 77.6% / 14.9% of operators | Pawlaczyk-Łuszczyńska et al., Noise and Health 2018 |
| Tinnitus after work / hyperacusis | 6.4% (95% CI 2.5% to 14.6%) / 15.4% (95% CI 8.9% to 25.2%) | Pawlaczyk-Łuszczyńska et al., Noise and Health 2018 |
| Headset use, 177 operators | 5.8 ± 1.8 h/day, 28.5 ± 9.9 h/week | Pawlaczyk-Łuszczyńska et al., Int J Occup Med Environ Health 2022 |
| Operators above 85 dB / 80 dB daily dose | 1.4% / 7.3% | Pawlaczyk-Łuszczyńska et al., Int J Occup Med Environ Health 2022 |
| Mean peak C-weighted level under headsets | 112.9 ± 8.2 dB | Pawlaczyk-Łuszczyńska et al., Int J Occup Med Environ Health 2022 |
| Mean daily exposure, 150 UK operators | 68 to 77 dBA, background noise 62 ± 2 dBA | Patel and Broughton, Ann Occup Hyg 2002, via NIOSH 2011 |
| Highest normalized exposure, dispatch centres | 75.5 dBA | Venet et al., Int J Occup Med Environ Health 2018 |
Context note: in the 2022 study, levels under the headset spanned 65 to 97 dB for call center operators, the highest of the three headset-using groups measured (Pawlaczyk-Łuszczyńska et al. 2022). Most recent available data: 2022.
6. Headset Hardware and Exposure Limits
The equipment itself can push agents toward the limits. Four of 12 communication headsets tested exceeded 85 dB at full volume, and the loudest, at 92.5 dB, would hit the daily criterion after just 1 hour 25 minutes (Kozlowski, IJERPH 2022). These were headsets for communication platforms on laptops rather than call centre systems with dedicated limiters, the kind of setup a home-based agent may rely on.
Headset design also changes the level agents choose. In a study of 79 operators with normal hearing, monaural headsets ran at 85.5 dBA against 83.1 dBA for binaural models, 84.8% of operators preferred binaural, and 98.7% reported at least one auditory symptom after headset use (Silva et al., American Journal of Audiology 2022). The regulatory limits below are the yardstick for all of these readings, and our manufacturing noise exposure statistics show how far louder industries sit against them.
| Metric | Value | Source |
|---|---|---|
| Communication headsets above 85 dB at 100% volume | 4 of 12 | Kozlowski, IJERPH 2022 |
| Monaural vs binaural headset level | 85.5 dBA vs 83.1 dBA (84.8% preferred binaural) | Silva et al., Am J Audiol 2022 |
| Operators reporting at least one auditory / nonauditory symptom | 98.7% / 88.6% of 79 | Silva et al., Am J Audiol 2022 |
| EU lower / upper action value / limit (daily) | 80 / 85 / 87 dB(A) | EU Directive 2003/10/EC |
| EU peak values | 135 / 137 / 140 dB(C) | EU Directive 2003/10/EC |
| US OSHA action level / permissible exposure (8 h) | 85 dBA / 90 dBA, impulse noise not to exceed 140 dB peak | OSHA 29 CFR 1910.95 |
| NIOSH recommended exposure limit | 85 dBA, 8-hour TWA | NIOSH Publication 2011-210 |
| Safe Work Australia exposure standard | 85 dB average over 8 h, 140 dB peak | Safe Work Australia, Noise |
Context note: the HSE expects call handlers to stay below the 80 dB lower exposure action value if noise risk is managed well (HSE, Acoustic shock guidance). The national limits are in EU Directive 2003/10/EC, OSHA 1910.95 and Safe Work Australia’s noise page. None of these daily-dose rules is designed to capture a single sub-second spike, which is why regulators such as WorkSafe WA handle acoustic incidents separately, through output limiters, training and incident policies.
7. The Workforce at Risk
The exposed population is large even in one country. The US employed 2,595,750 customer service representatives in May 2025 (BLS Occupational Employment and Wage Statistics), plus public safety telecommunicators and telemarketers, all roles built around the phone. As an illustration only, a 1% incidence applied to that base would be 0.01 x 2,595,750 = about 26,000 workers, which is why the lack of incident surveillance is the core data gap.
The broader hearing picture is a reminder that office-based service work is not quiet by default. Across 1.9 million US audiograms, workers in the Administrative and Support Services sector (NAICS 561) showed a hearing loss prevalence of 14.50%, with a prevalence ratio of 1.13 against the reference industry (Sekhon et al., International Journal of Audiology 2020).
| Metric | Value | Source |
|---|---|---|
| US customer service representatives, May 2025 | 2,595,750 | BLS OEWS May 2025 |
| Mean annual wage, customer service representatives | $46,590 | BLS OEWS May 2025 |
| US public safety telecommunicators / telemarketers | 102,500 / 58,430 | BLS OEWS May 2025 |
| Share of UK working population in call centres | An estimated 2% | Lawton, Proceedings of the Institute of Acoustics 2003 |
| Audiograms analyzed / Services sector workers among them | 1.9 million / 158,436 (2006 to 2015) | Sekhon et al., Int J Audiol 2020 |
| Hearing loss prevalence, Administrative and Support Services (n = 32,714) | 14.50% (95% CI 14.12 to 14.88), PR 1.13 (95% CI 1.09 to 1.16) | Sekhon et al., Int J Audiol 2020 |
| Hearing loss prevalence, Services sector vs all industries | 17% vs 16% | Sekhon et al., Int J Audiol 2020 |
Context note: the Sekhon figures cover noise-exposed workers with audiograms in a NIOSH dataset, not call centre agents specifically, and the paper notes that health hazards from high noise levels at call centers have been documented before (Sekhon et al. 2020). Most recent available data for the UK share: 2003.
Summary: Call Center Acoustic Shock by the Numbers
| Metric | Value | Source |
|---|---|---|
| Pain / tinnitus / hyperacusis among 103 operators after 123 incidents | 95% / 50% / 32% | Westcott, Acta Oto-Laryngologica 2006 |
| Danish operators who had an acoustic shock | 22% of 90 | Hinke and Brask 1999, via AudiologyOnline 2002 |
| Acoustic shocks recorded among 39 dispatchers, shifts up to 12 h | 0 | Venet et al., Int J Occup Med Environ Health 2018 |
| Estimated share of call center workers affected | Nearly 13% | John et al. 2015, cited in Trends in Hearing 2018 |
| Medico-legal cases with normal audiometry | 43% of 30 | Parker et al., Int J Audiol 2014 |
| Woodings v BT settlement per claimant | GBP 500 to GBP 750 | Solicitors Journal 2007 |
| Diagnosed call center operators later dismissed | 43.8% | Altundaş Hatman and Torun, Med Lav 2022 |
| Frequency / intensity of triggering sounds | 2.3 to 3.4 kHz / 82 to 120 dB SPL | Milhinch, AudiologyOnline 2002 |
| UK headset limiter ceiling | 118 dB, standard since 1991 | HSE, Acoustic shock guidance |
| Typical exposure before headset removal | 5 to 15 seconds | Lawton, Proceedings of the Institute of Acoustics 2003 |
| Mean daily dose, 78 operators | 74.7 dBA | Pawlaczyk-Łuszczyńska et al., Noise and Health 2018 |
| Operators above 85 dB daily dose | 1.4% of 177 | Pawlaczyk-Łuszczyńska et al., Int J Occup Med Environ Health 2022 |
| Loudest communication headset at full volume | 92.5 dB, 1 h 25 min to the daily criterion | Kozlowski, IJERPH 2022 |
| Operators with at least one auditory symptom after headset use | 98.7% | Silva et al., Am J Audiol 2022 |
| EU daily action values / limit | 80 / 85 / 87 dB(A) | EU Directive 2003/10/EC |
| US customer service representatives | 2,595,750 | BLS OEWS May 2025 |
Methodology and Sources
- Westcott M., Acoustic shock injury (ASI), Acta Oto-Laryngologica 2006: author-hosted PDF
- Milhinch J.C., Acoustic Shock Injury: Real or Imaginary?, AudiologyOnline 2002 (also our source for Hinke and Brask 1999): AudiologyOnline
- McFerran D., Acoustic shock, Canadian Audiologist 2015: Canadian Audiologist
- Noreña A.J. et al., An Integrative Model Accounting for the Symptom Cluster Triggered After an Acoustic Shock, Trends in Hearing 2018 (our source for the John et al. 2015 estimate): PMC6156190
- Pawlaczyk-Łuszczyńska M. et al., Noise exposure and hearing status among call center operators, Noise and Health 2018: PMC6301089
- Pawlaczyk-Łuszczyńska M. et al., Noise exposure and hearing status among employees using communication headsets, Int J Occup Med Environ Health 2022: PMC10464809
- Kozlowski E., Noise Parameters of Headsets Designed for Communication Platforms, IJERPH 2022: PMC8955439
- Altundaş Hatman E., Torun S.D., Occupational diseases among call center operators needing vocal rehabilitation, Med Lav 2022: PMC9437654
- Sekhon N.K. et al., Prevalence of hearing loss among noise-exposed workers within the services sector, 2006-2015, Int J Audiol 2020: PMC10040315
- Lawton B.W., Audiometric Findings in Call Centre Workers Exposed to Acoustic Shock, Proceedings of the Institute of Acoustics 2003: University of Southampton PDF
- Parker W. et al., ‘Acoustic shock’: a new occupational disease?, Int J Audiol 2014; Silva B.G. et al., Noise Exposure, Headsets, and Auditory and Nonauditory Symptoms in Call Center Operators, Am J Audiol 2022; Venet T. et al., Auditory fatigue among call dispatchers working with headsets, Int J Occup Med Environ Health 2018 (abstract data read via the Europe PMC database)
- UK Health and Safety Executive, Acoustic shock guidance: HSE
- NIOSH, Reducing Noise Hazards for Call and Dispatch Center Operators, Publication 2011-210 (our source for Patel and Broughton 2002): CDC NIOSH
- WorkSafe Western Australia, Noise management in call centres: WorkSafe WA
- ITU-T Recommendation P.360 (07/2006): ITU summary
- EU Directive 2003/10/EC: EUR-Lex; US OSHA 29 CFR 1910.95: OSHA; Safe Work Australia, Noise: Safe Work Australia
- US Bureau of Labor Statistics, Occupational Employment and Wage Statistics May 2025: BLS OEWS
- Solicitors Journal, A shock to the system, 2007 (Woodings v British Telecommunications plc): Solicitors Journal
- Data watch: Westcott 2006 and Milhinch 2002 describe the same Australian case set (103 people, 91 female and 12 male) but differ on details: study years (1994 to 1999 vs 1995 to 1999), hyperacusis (32% vs 38%), hearing loss (18.4% vs 18%) and trigger intensity (82 to 110 vs 82 to 120 dB SPL). Westcott’s 95% figure is any pain, while Milhinch’s 81% is ear pain. The Danish peak level is given as 108 dB SPL by Milhinch and 100 dB by McFerran. The Ayugi et al. 2016 survey is reported as 384 (13%) of 1,351 operators, but 384 / 1,351 works out to 28.4%, so the published percentage and the counts cannot both be right; we report both as published and could not access the original paper. The nearly 13% estimate is attributed to John et al. 2015 and is quoted second-hand. Most data in this roundup predates 2023 because no agency publishes acoustic shock surveillance. Pawlaczyk-Łuszczyńska et al. 2022 say their questionnaire results on tinnitus and hyperacusis will be published separately.
Last updated: October 18, 2026. We update this roundup quarterly, and the next refresh is expected when the BLS publishes its May 2026 Occupational Employment and Wage Statistics.