What is noise? Noise is any unwanted sound originating from production process equipment or work tools that, at certain levels, can cause hearing impairment. (Ministry of Manpower Regulation No. 5 of 2018).

What is the normal noise exposure limit (NEL)?

The following are the international daily noise exposure limits and those based on Ministry of Manpower Regulation No. 5 of 2018:

1. 8 Hours: 85 dBA
2. 4 Hours: 88 dBA
3. 2 Hours: 91 dBA
4. 1 Hour: 94 dBA
5. 30 Minutes: 97 dBA
6. 15 Minutes: 100 dBA
7. 7.5 Minutes: 103 dBA
8. 3.75 Minutes: 106 dBA
9. 1.88 Minutes: 109 dBA
10. 0.94 Minutes: 112 dBA
11. 28.12 Seconds: 115 dBA
12. 14.06 Seconds: 118 dBA
13. 7.03 Seconds: 121 dBA
14. 3.52 Seconds: 124 dBA
15. 1.76 Seconds: 127 dBA
16. 0.88 Seconds: 130 dBA
17. 0.44 Seconds: 133 dBA
18. 0.22 Seconds: 136 dBA
19. 0.11 Seconds: 139 dBA

The National Institute for Occupational Safety and Health (NIOSH) has recommended that all worker exposures to noise should be controlled below a level equivalent to 85 dBA for eight hours to minimize hearing impairment due to workplace noise.

What are the health effects of noise?

• Auditory: Permanent Noise-Induced Hearing Loss (NIHL)
• Non-Auditory:
  • Physiological disturbances: Increased blood pressure, increased pulse rate, increased basal metabolism, vasoconstriction of blood vessels, increased muscle tension (increased stimulation to the autonomic nervous system).
  • Psychological disturbances: Stress, fatigue, emotional distress, communication and concentration disorders.

How to prevent it?

In 1981, OSHA implemented new requirements to protect all workers in general industry (e.g., manufacturing and service sectors) by requiring employers to implement a Hearing Conservation Program (HCP) where workers are exposed to time-weighted average noise levels of 85 dBA or higher over an 8-hour work shift. The Hearing Conservation Program consists of 7 components:

1. Identification and analysis of noise sources;
2. Noise and administrative control;
3. Periodic audiometric testing;
4. Personal protective equipment;
5. Worker motivation and education;
6. Data recording and reporting;
7. Program evaluation.

Periodic Audiometric Testing

• Conducted pre-employment, pre-placement, and annually for workers at risk of noise exposure.
• If noise intensity is ≥ 85 dB, testing should be done every 6 months after pre-employment for the first 2 years.
• Calibrated audiometry equipment and soundproof room.
• Trained and competent examiner.
• Preparation of workers for the test (noise-free for at least 12-14 hours).

Noise-induced hearing loss is a permanent sensorineural hearing loss that cannot be treated with medication or surgery, making prevention crucial.

HEARING FUNCTION EXAMINATION

To assess hearing, it is necessary to conduct both air and bone conduction tests using qualitative (tuning fork), semi-quantitative (Whisper Test), and quantitative (pure-tone audiometry) methods.

Tuning Fork Tests

These tests are qualitative and aim to assess the presence of hearing loss and differentiate between conductive and sensorineural hearing loss. Various tuning fork tests according to Soetirto and Hendamin (1997) include:

• Rinne Test: Compares air conduction and bone conduction in the tested ear, aiding in the diagnosis of conductive hearing loss.
• Weber Test: Conducted after the Rinne test to compare bone conduction between the left and right ears.
• Schwabach Test: Compares bone conduction in the tested ear with that of the examiner's normal hearing.
• Bing Test (Occlusion Test)
• Stenger Test

Whisper Test This semi-quantitative test determines the degree of hearing loss roughly. It should be conducted in a quiet room without echo, with a minimum length of 6 meters (Al-Fatih, 2008).

Pure-Tone Audiometry This quantitative test assesses the degree and localization of hearing loss. The results are displayed in an audiogram, which is created using an audiometer (Soetirto and Hendarmin, 1997).

BERA (Brainstem Evoked Response Audiometry) This objective and non-invasive test evaluates brain electrical potentials in response to sensory stimuli such as sound. It is beneficial for testing infants, children with behavioral issues, mental retardation, and decreased consciousness.

Author: Dr. Iman Susanto (Medical Service Doctor at Pramita Clinical Laboratory, Jl. Samanhudi No. 21, Central Jakarta)