Noise and Vibration Hazards

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What is Sound?

Sound is –

  • A form of energy
  • A pressure wave.
  • Produced by vibrating of objects

The instrument by which sound is measured simply called a Digital sound level meter.

Sound waves ought to travel through a medium like a solid, liquid, or gas.

 

 

Sound Measurement Facts

  • Sound energy travels in waves;
  • The wave is made up of pressure of differences;
  • Sound is measured in decibels (Common Unit) and Pascal’s;
  • The tradition unit of energy measurement was the joule;
  • Measurement depends on frequency and amplitude;
  • The intensity of sound is measured in sound pressure levels (SPL).

 

What Is Noise?

The word “noise” is derived from the Latin word “nausea”, meaning seasickness. Therefore, noise means any unwanted sound that disturbs people and makes it difficult to hear.

 

For example, conversations of other people may be called noise by people not concerned in any of them; any unwanted sound like domesticated dogs barking, road traffic sound or a distant aircraft in the quiet countryside is termed noise.

 

 

Difference Between Sound and Noise

Sound

Noise

Pleasant to hear

Unpleasant sound

Desirable

Undesirable

Relevant

Irrelevant

Regular fluctuations of vibrations

Irregular fluctuations of vibrations

 

 

How Can Sound or Noise Be Produced?

A noise problem typically consists of 3 inter-related parts-

  1. The Source
  2. The Receiver and
  3. The Transmission Path

How-Can-Sound-or-Noise-Be-Produced.

 

 

Properties Of Noise

– Loudness/Intensity

  • Normal Conversation – 60 DB
  • Recommended Maximum – 85 DB
  • Threshold ff (final fantasy) Pain – 140 DB
  • Mechanical Damage – 150 DB

– Frequency: Human ear can hear frequencies from 20 HZ to 20,000 HZ

 

 

Major Causes/Sources of Noise Pollution

  • Road Traffic Noise
  • AirCraft
  • Noise from Railroads
  • Construction Noise
  • Noise in Industry
  • Noise in Building
  • Loud Speakers/ Public Address System
  • Fireworks

 

 

Top 6 Causes of Noise Pollution

  1. Construction Activities
  2. Household Chores
  3. Industrialization
  4. Poor Urban Planning
  5. Social Events
  6. Transportation

Noise Exposure Will Cause Two Styles of Health Effects. Effects of noise pollution –

  1. Auditory Effects: Auditory fatigue, Deafness (Temporary or Permanent)
  2. Non-Auditory Effects: Annoyance, Loss of working efficiency, Interference in speech communication, Physical disorder like increase in heartbeats etc.

 

 

Signs of Hearing Loss

  • Difficult of hearing people’s speaking;
  • Inability to listen to an explicit high-pitched or soft sound;
  • Noise or ringing in ears;
  • Getting complaints that the radio or TV is too loud;
  • Distance affects the intensity of sound;
  • If you are far away, the power is greatly diminished;
  • Any sound above 85 DB can cause hearing loss;
  • The loss is said to the intensity and length of exposure.

 

Causes of Hearing Loss

  • Aging Facts
  • Illness
  • Noise Exposure

 

Is there a safe level of noise?

An alleged safe level of noise depends on the volume and the way long you’re exposed to that. In most countries the standards usually refer to 85 dBa over an eight-hour workday.

 

If employees area unit exposed to higher amplitude with none type of hearing protection, the exposure time should be reduced, either by rotating employees or providing longer rest periods.

 

Recommended limited noise levels for the number of hours exposed

Number of hours exposed

Sound level dBa

8

85 – 90

6

92

4

95

3

97

2

100

1.5

102

1

105

30 minutes

110

15 minutes

115

 

 

How does 85 dBa compare with everyday sound?

Effects on human beings

Sound level in dBa

Sound Source

Highly Injurious

Jet engine

140

River hammer

130

Injurious

Chain saw

120

Heavy truck

90

Risk

Car

80

Little risk

Conversation

70

Whispering

30

 

Standards For Sound

Sl. No.

Category of Areas

Standards determined at dBa unit

Day

Night

a.

Silent zone

45

35

b.

Residential area

50

40

c.

Mixed area (mainly residential are, also simultaneously used for commercial and industrial purposes)

60

50

d.

Commercial

70

60

e.

Industrial area

75

70

Notes:

  1. The time from 6 a.m. to 9 p.m. is counted as day time.
  2. The time from 9 p.m. to 6 a.m. is counted as night time.
  3. The area up to a radius of a hundred meters around hospitals or academic institutions or special institutions/establishments identified/to be identified by the Govt. is designated as Silent Zones wherever use of horns of vehicles or there audio signals, and loudspeakers are prohibited.

 

 

Occupation Safety and Health Administration (OSHA)

OSHA Daily Permissible Noise Level Exposure

Hours per day

Sound level

8

90 dB

6

92 dB

4

95 dB

3

97 dB

2

100 dB

1.5

102 dB

1

105 dB

.5

110 dB

.25 or less

115 dB

OSHA is the workplace of the United States Department of Labor

 

 

The National Institute for Occupational Safety and Health (NIOSH)

NIOSH Daily Permissible Noise Level Exposure

Hours per day

Sound level

8 85 dBa
6 86 dBa
4 88 dBa
3 89 dBa
2 90 dBa
1.5 92 dBa
1 94 dBa
.5 97 dBa
.25 or less 100 dBa
0 112 dBa
NIOSH is the U.S. federal agency

 

 

How Can We Management or Control Noise?

3 proven techniques used for noise management –

  1. Management at supply
  2. Management within the Transmission Path
  3. Using Protective Equipment

 

 

We should have to wear hearing protection (PPE) at home and work when:

▪ In high noise areas;

▪ Using power tools;

▪ Using impact tools;

▪ In the generator & the boiler room;

▪ In the sewing section.

International Labor Organization (ILO)

 

Points to remember when wearing ear protection as per ILO:

  • In hot and humid conditions workers don’t feel comfortable in wearing PPE;
  • Workers can’t communicate easily if they are wearing hearing protection which can be a problem in case of an emergency;
  • Earplugs and ear muff are must be thoroughly tested before use and regularly cleaned, repaired and replaced;
  • Workers must be given training in the correct use of PPE.

Vibrations

What is Vibration/What is the Theory of Vibration?

By Vibration We Mean-

  • The act of vibrating.
  • The condition of being vibration.
  • Rapid linear motion of a particle or an elastic solid about an equilibrium position.

Therefore, any motion that repeats itself after some time is considered as vibration.

 

 

Why do we care about vibration?

Vibration is:

  • Wasted energy
  • A major cause of premature component failure
  • Causing noise pollution

Classification of Vibration

There are two types of vibrations:

  1. Hand-arm vibration,
  2. Body vibration.

 

Hand-arm vibration: Vibrations transferred to hand and arm joints are called hand-arm vibration. Extreme hand-arm vibrations can seriously damage blood vessels and joints in the fingers and hands.

 

Body vibration: Vibrations transferred to the entire body are considered as a body vibration. Body vibration can cause fatigue, headaches, gastric, spinal (back) cord and balance organ abnormalities.

 

 

Preventive Measure

  • Appropriate design of machines;
  • Acquisition of materials and vehicles that cause the least vibrations;
  • Machines should be well maintained;
  • Preferably use tools with vibration damping hand clasps or vibration damping gloves;
  • Limit the exposure duration as much as possible.

 

 

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