Noise-induced hearing loss and hearing conservation at work
- Topic
Loud, repeated noise permanently damages the cells of the inner ear; it is prevented by controlling noise and checking hearing with audiograms.
What it is
Noise-induced sensorineural hearing loss (NIHL) is one of the most common occupational diseases and it is preventable. In Colombia the reference is the evidence-based Comprehensive Care Guideline for Noise-Induced Sensorineural Hearing Loss in the Workplace (GATI-HNIR), published by the Ministry of Social Protection in 2006. It sets the exposure limit, the order of control measures, the medical surveillance programme with audiometry and the criteria for referral to ENT. The WHO adds the risk of recreational noise and unsafe listening in young people.
Key facts
- The Colombian guideline is the GATI-HNIR of the Ministry of Social Protection (December 2006), checked on the Ministry of Health website on 2026-11-05.
- Medical surveillance for every worker exposed to 80 dBA or more as a time-weighted average: medical assessment, screening questionnaire and audiometry.
- Pure-tone audiometry at 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz in each ear, by qualified staff in a sound-treated booth.
- Pre-employment and exit audiograms after at least 12 hours of auditory rest, which cannot be replaced by wearing hearing protectors.
- Follow-up audiograms at the end of, or late in, the work shift, to pick up temporary threshold shifts.
- If the threshold recovers it is a temporary shift (reinforce the programme); if it persists, the company reassesses exposure and refers to occupational medicine or ENT.
- Besides noise, the guideline asks about noisy hobbies, chemicals and vibration; NIOSH points out that ototoxic chemicals add risk.
Step by step
- Ask about the job, years of exposure, protection used, recreational noise, chemicals and vibration.
- Ask about symptoms: tinnitus, muffled sounds after leaving work, trouble understanding speech in noise.
- Do otoscopy to exclude wax impaction or otitis before reading the audiogram.
- Compare the current audiogram with the pre-employment one, frequency by frequency, without averaging.
- Shift of 15 dB or more: repeat at once and, if it persists, confirm within 30 days.
- If confirmed, review noise control and hearing protection with the employer.
- Apply the ENT referral criteria and report it as a possible occupational disease.
Frequency of follow-up audiometry by exposure (GATI-HNIR)
| Noise exposure (8-hour time-weighted average) | Follow-up audiometry |
|---|---|
| 80 to under 82 dBA | Every 5 years |
| 82 to 99 dBA | Yearly |
| 100 dBA or more | Every 6 months |
In clinical practice
- Signs of overexposure the worker notices: ringing ears or dull sounds after leaving a noisy area, or turning up the phone volume at the end of the shift.
- NIOSH rule of thumb: if at 85 dBA you must raise your voice to talk at about one metre (3 feet), and at 95 dBA or more you must shout, the setting is hazardous.
- A unilateral or clearly asymmetric loss is not typical of occupational noise: it needs individual assessment.
- The WHO estimates that over 1 billion young adults are at risk of permanent hearing loss from unsafe listening (personal audio devices, concerts, clubs).
Next step / Initial management
- Initial workup: otoscopy and air-conduction pure-tone audiometry from 500 to 8000 Hz, with bone conduction if in doubt; compare with the baseline.
- Management: reduce exposure with control at the source, ensure hearing protection with a corrected noise reduction rating, and rehabilitate with hearing aids if the loss affects communication.
- Routine referral to ENT (GATI-HNIR criteria): significant ear symptoms in the past year (earache, vertigo) or thresholds of 25 dB or more at 500, 1000 or 2000 Hz.
- Also refer for an interaural asymmetry of 15 dB or more at 500 to 2000 Hz or 30 dB or more at 3000 to 6000 Hz, or a change from baseline of 15 dB (500 to 2000 Hz) or 20 dB (3000 to 6000 Hz).
- Same-day referral if the loss is sudden: it is not chronic noise damage until proven otherwise.
Test yourself
Think of the answer, then tap the question to see it.
A worker in a metal plant has a bilateral notch at 4000 Hz with recovery at 8000 Hz. What is the most likely diagnosis?
Noise-induced sensorineural hearing loss. A bilateral, symmetric notch at 3000 to 6000 Hz, deepest at 4000 Hz, is typical.
According to Colombia's GATI-HNIR, what is the permissible noise exposure limit and with what exchange rate?
85 dBA as an 8-hour daily time-weighted average, with a 3 dB exchange rate.
A worker's yearly audiogram shows a 15 dB drop at 4000 Hz compared with baseline. What is done?
Repeat the audiogram at once, controlling sources of error; if the drop persists, do a confirmation audiogram within 30 days under the same conditions as the baseline.
Why are hearing protectors not the first noise control measure in the Colombian guideline?
Because engineering control at the source and along the transmission path comes first; personal protective equipment is a temporary measure until those controls are in place.
Connections
Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.
Sources: Guía de Atención Integral Basada en la Evidencia para Hipoacusia Neurosensorial Inducida por Ruido en el Lugar de Trabajo (GATI-HNIR) (Ministerio de la Protección Social, República de Colombia, 2006); Noise-Induced Hearing Loss (Centers for Disease Control and Prevention, NIOSH, 2024); Deafness and hearing loss (fact sheet) (World Health Organization, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.