This document discusses hearing conservation and prevention of noise-induced hearing loss in industrial workplaces. It covers the effects of noise on workers, anatomy of the ear, noise-induced hearing loss, selection and use of hearing protectors, employer and worker duties, permissible noise exposure limits, noise control methods, and audiometric testing requirements. The key points are: excessive workplace noise can cause temporary or permanent hearing loss; employers must control noise levels and provide hearing protectors; workers must use protectors and undergo annual hearing tests; and noise levels are not to exceed 85dB over 8 hours according to regulations.

1. Hearing Conservation
and Prevention
Walton Hi-Tech Industries Ltd.

2. Contents
1. Introduction
1.1. General
1.2 Effects on workers
2. The Effects of Noise Hearing
2.1 How sound reach us
2.2 The anatomy of the ear
2.3 How we hear
3. Selection and Use of Hearing Protectors
3.1 Ear plugs
3.2 Ear muffs
3.3 Selection of hearing protectors

3. Contents
4. Requirements
4.1. The employer’s duties
4.2 The worker’s duties
4.3 Permissible Exposure Limit
5. Noise Control
5.1 Administrative Control
5.2 Engineering Control
6. Audiometric Testing
Appendix 1 develop country requirements.
“Less Noise for Healthier Hearing”
Appendix 2 The Factories (Noise) Regulation

4. Introduction to
Industrial Noise
1.1 General
Noise is unwanted sound
• noise reaches workers’ ear from many sources.
• some common noisy processes:
pneumatic chipping, hacking of concrete, metal stamping.

5. Introduction to Industrial Noise
Noise levels (intensity)
• measured in decibels (dB).
• ranges from 0dB to over 140dB

6. Introduction to Industrial Noise
Noise pitch (frequency)
• measures in hertz (Hz) or cycles.
• Example, high frequency noise-bird song
low frequency noise- man’s deep voice.

8. Introduction to Industrial Noise
1.2. Effects on workers
(I) Psychological
- annoy and disrupt concentration.
(II) Interference with Communication by
speech
- interference with job performance.
- instructions/ messages not clearly heard.
- results in miscommunication and accidents.

9. Introduction to Industrial Noise
1.2. Effects on workers
(III) Physiological Effects
- Noise induced deafness or NID.(irreversible)
- Tinnitus (ringing in the ear)
- Temporary deafness (reversible)
Note: Exposure is cumulative-the longer or higher the
exposure, the worse the effect on the ears.

10. The Effects of Noise on hearing
2.1 How sounds reaches us

11. The Effects of Noise on hearing
Anatomy of the Ear

12. 2.2 The Anatomy of the Ear
The human ear is composed of three major sections:
- external, middle and inner ears.
- each has a distinct function.
- external ear captures and funnels sound waves to
middle ear.
- middle ear consists of ear drum and chain of three
bones, rest at one end against ear drum, the other
end connected to inner ear.
The Effects of Noise on hearing

13. 2.2 The Anatomy of the Ear
- inner ear consists of a spiral tube filled with fluid called
cochlea.
- spiral tube contains sensory cells with delicate hairs
or hair cells projecting into the fluid.
- connected to nerve fibres which carry messages to our
brain.
The Effects of Noise on hearing

14. The Effects of Noise on hearing
2.3 How we hear
- ear drum vibrates, chain of bones in middle ear
is set in motion.
- vibrate the fluid of inner ear.
- when fluid vibrates, hair cells are stimulated,
sending nerve currents or impulses to the brain.
- brain interprets these as sound.

15. The Effects of Noise on hearing
2.3 How we hear
- exposure to excessive noise over long period
can cause hair and nerve cells to wear out.
- resulting in permanent loss of hearing.
- cells also deteriorate with age.
- premature deafness due to exposure to
excessive noise can be prevented.

16. The Effects of Noise on hearing
2.4 Hearing Loss
- defined as any reduction in the ability to hear of a ‘normal’
person.
- classified into 2 categories:
TEMPORARY HEARING LOSS
- exposure to loud noises for few hours, hearing return
after a rest period.
- recovery period depending on individual, the severity and
length of exposure.

17. The Effects of Noise on hearing
2.4 Hearing Loss
PERMANENT HEARING LOSS
- result of diseases, injury, or exposure to loud noises
for
extended period of time.
- hearing loss associated with exposure to industrial
noise is called noise induced deafness or NID- it
is not reversible.
- total hearing loss is most frequently associated with
disease or traumatic injury.

18. Selection & use of hearing
protectors
3.1 Ear Plugs
• made of plastic foam,
cotton
• inserted into external ear.
• must be fitted properly.
• slight leakage reduces
effectiveness.

19. Selection & use of hearing
protectors
3.2 Ear Muffs
• worn over the head
• cover the external ear.
• more effective than ear
plugs.
• need regular maintenance.
Note: Long hair should be pushed out of the way as it reduces effectiveness.

20. Selection & use of hearing
protectors
3.3. Selection of Hearing Protectors
1. Noise Monitoring Officer (NMO)
- measures noise levels.
- reduce/ bring noise levels at the workers’ ear to below
85dbB.
- consults suppliers on noise reduction.
- type of hearing protectors suitable.

21. Selection & use of hearing
protectors
3.3. Selection of Hearing Protectors
- suitable type of protectors to issue to workers.
- conduct training to workers on how to use it
properly.
- planned cleaning/ maintenance schedule for
non-disposable types.

22. Some develop country Legal
Requirements as follows:
4.1. The Employer’s (Occupier’s) Duties
Factories Act Cap. 104
- employers to reduce (as is practicable), the exposure of
their employees to excessive noise or vibration.
Factories (Noise) Regulation 1996
- to reduce exposure by controlling the noise produced
by machinery or processes.
- not more than 85dB over an 8-hour work day.

23. Some develop country Legal
Requirements as follow:
4.1. The Employer’s (Occupier’s) Duties
- >10 workers are exposed to excessive noise,
employer must arrange for noise survey every 3 years.
- >50 workers are exposed to excessive levels,
employer must appoint Noise Monitoring Officer
to advise on noise control measures.

24. some develop countries
requirements as follow:
4.1. The Employer’s (Occupier’s) Duties
Factories (Medical Examinations) Regulations
- employer must provide audiometry test for
employees exposed to excessive noise.
Section 67 of Factories Act Cap 104
- Noise Induced Deafness (NID)-a notifiable disease.
- NID also compensatible disease under Workmen’s
Compensation Act.

25. Requirements
4.2 The Workers’ Duties
- worker must use all safety devices provided.
- includes using hearing protectors.
-must not willfully interfere or misuse them.
- employee must undergo audiometric test when
company requested .

26. Requirements
4.3 Permissible Exposure Limit
Sound Level, dB(A) Duration limit per day
85 8 hr
88 4 hr
91 2 hr
94 1 hr
97 30 min
100 15 min
103 7.5 min
106 4 min
109 2 min
112 or more less than 1 min

27. Noise Control
5.1. Administrative Control
1. Operate noisy machinery on shifts when fewer employees
are present
2. Rotate employees out of noisy environments for part of
their shift.

28. Noise Control
5.2. Engineering Control
1. Construct acoustics enclosures and noise barriers.
2. Installing silencers and mufflers at exhaust opening
of machines.
3. Substituting noisy machines and processes with less
noisy ones.
4. Applying damping materials to reduce surface
vibration.
5. Ensure that machinery is maintained regularly.

29. Audiometric Test
6. Hearing Test
- hearing of each ear tested separately at a
range of frequencies.
- find out the audible threshold--the softest sound
at that frequency that worker can hear.
- print-out is obtained.
- repeat test next year, any reduction in worker’s
hearing at different frequencies can be picked up.

30. Audiometric Test
6. Hearing Test
- Audiometric examinations carried out by designated
factory doctor.
- DFD must undergone a course in audiometry
approved by Chief Inspector.
- workers exposed to excessive noise must undergo
audiometric examinations at start of employment in the
noisy process, thereafter annually.

31. Audiometric Test
6. Hearing Test
- Audiometry cannot reverse or cure NID.
- it is only a medical tool for identifying a
worker with NID.
- measuring by how much worker’s hearing has
been effected.

32. Thank you All
Any Questions?