Noise-Induced Hearing Loss: Spotting It Early

Why is occupational hearing loss noticed late?

Occupational hearing loss is permanent damage done over the years by workplace noise to the sensory cells of the inner ear. It does not hurt, it does not appear overnight, and the first sounds affected are not the most prominent sounds of everyday speech. So employees do not notice the problem until their family says "you have the TV turned up too loud", or until they can no longer pick out conversations in a crowded place.

The list of occupational diseases describes this course in two stages (Regulation on Procedures for Determining the Rate of Loss of Working Capacity and Earning Capacity in the Profession Annex 2, E-3). The first stage is auditory fatigue: a temporary reduction in hearing. The second is the manifestation stage: the hearing loss no longer reverses; it starts at high frequencies and then spreads to speech frequencies. The list also states that this loss is usually bilateral and does not progress after exposure ends. The practical conclusion is clear: the only way to stop the loss is to reduce exposure early.

Noise-induced hearing loss can occur in any job with high noise levels; however, among its example jobs, the list explicitly names weaving looms and other noisy machines and looms in the textile industry. Weaving and spinning businesses, metalworking and press lines in Bursa and the surrounding provinces should therefore give priority to hearing in health surveillance.

Early signs: tinnitus and "temporary" deafness

Ringing in the ears is the earliest and most often ignored sign of workplace noise. A buzzing or ringing in the ears or a "cotton wool" feeling at the end of a shift shows that the inner ear has been overloaded that day. Even if these symptoms pass within a few hours, their recurrence suggests that permanent damage is approaching.

Employees and foremen should be taught to report these signs to the workplace physician:

• Ringing or buzzing in the ears at the end of a shift
• Sounds seeming muffled for a while after leaving work
• Being unable to make out speech in noisy surroundings or in a crowd
• Difficulty understanding conversations on the phone
• Having more difficulty hearing high-pitched voices such as women's and children's voices
• Ringing that is constant or more noticeable in the quiet of the night

An employee with any of these signs should be referred to the physician without waiting for the periodic examination date. Art. 13 of the Noise Regulation does not limit health surveillance to regular intervals either; it also lists cases deemed necessary by the risk assessment results and the situations listed in Art. 15 of Law No. 6331 as grounds for examination.

Acoustic trauma: a single sudden sound

Unlike chronic hearing loss, acoustic trauma is caused by a single event such as an explosion, a compressed air discharge or an impulsive sound very close by. Sudden loss of hearing, ringing, sometimes pain in the ear and one-sided effects may be seen. In this case the employee is referred to the physician without delay. Because it is linked to a single event, the incident is also assessed separately for work accident recording and reporting.

Who is at greater risk?

Not everyone working in the same hall has the same risk. The following groups should be addressed separately in the risk assessment and health surveillance plan:

For noise values and the rule on when hearing protection is taken into account, see our article The Noise Regulation: 80, 85 and 87 dB, and for the measurement method, workplace noise measurement.

What to do when audiometry detects a loss

A hearing test often shows a loss before the employee notices it. Art. 13/2 of the Noise Regulation lists what to do when noise-induced hearing loss is detected. Apply these steps at the workplace in the following order:

1. Inform the employee. The workplace physician explains the result and what it means to the employee. Health information is confidential; the result is not shared with the foreman or co-workers, and only the information needed regarding fitness for work is passed to the employer.
2. Confirm the result. To distinguish temporary hearing reduction from permanent loss, the physician may ask for the test to be repeated or for further assessment.
3. Review the risk assessment. Is the measurement up to date, and are the employee's workstation and exposure time correctly defined? A new machine or shift pattern may have increased exposure.
4. Review the measures. Can the noise be reduced at source? Has the hearing protection been chosen correctly, is it fitted correctly and is it worn throughout the shift?
5. Change the job if necessary. The regulation explicitly lists measures such as assigning the employee to other work where they will not be exposed to noise.
6. Look at employees with similar exposure. The health of those working in the same department is reviewed and they are placed under regular health surveillance.
7. Assess a suspected occupational disease. If the physician thinks the loss may be work-related, the employee is referred to an authorised healthcare provider for diagnosis.

Hearing loss is not only a health outcome; it is also a workplace safety input. An employee whose hearing at high frequencies is reduced may be late to notice a forklift horn, a reversing alarm, the sound of a machine fault or a fire alarm. When assessing the workstation of an employee found to have a loss, ask this question too: are warnings in this department given only by sound? If necessary, adding light signals and flashing alarms protects both this employee and other employees wearing hearing protection. Whether the alarm is perceived by everyone in every department should also be checked in the emergency drill.

The last step shows why the pre-employment test should not be skipped: without a test on recruitment, it becomes difficult to show how much of a loss found later arose at this workplace. For the diagnosis and reporting steps see our article on what an occupational disease is, diagnosis and reporting, and for the structure of the list our article on the list of occupational diseases.

Preventing permanent loss: the workplace programme

Spotting it early only works within a programme. In noisy workplaces, a hearing conservation programme consists of these parts:

• Measurement and mapping: It should be known what the exposure is in which department and job; areas where 85 dB(A) is exceeded should be marked.
• Reduction at source: Machine maintenance, vibration isolation, enclosures and separating noisy work.
• Hearing protection: Type and size suited to the person, training on correct fitting and checks on use. For selection principles, see our article on PPE selection.
• Hearing tests: A baseline test on recruitment, then repeats at intervals set by the physician. We plan the tests with authorised healthcare providers.
• Training: Employees recognising and reporting the early signs.

In Bursa Sistemer's health surveillance and workplace physician services, hearing tests are assessed together with noise measurement results. For recommendations specific to weaving businesses see our article on OHS in weaving businesses and our textiles sector page; you can track test dates with the OHS calendar tool.

Frequently Asked Questions

Is tinnitus an occupational disease?

On its own it is not a diagnosis, but it is one of the early signs of noise-induced hearing damage. An employee who experiences ringing after a shift should be referred to the workplace physician and their exposure reviewed.

Does noise-induced hearing loss reverse?

Auditory fatigue in the first stage is temporary. In the permanent stage, however, the loss does not reverse; it usually does not progress after exposure ends. This is why measures should be taken before permanent loss begins.

Can an employee found to have hearing loss be dismissed?

The regulation provides for protective measures by the employer, such as assigning the employee to work where they will not be exposed to noise. The decision should be based on the workplace physician's assessment and the fitness-for-work result.

Is a hearing test required on recruitment?

Hearing tests are mandatory for employees who will be exposed to noise above 85 dB(A), and the pre-employment test forms the baseline against which later tests are compared. The pre-employment audiogram is also used in occupational disease assessment.