The document discusses noise pollution and its effects. It defines noise as unwanted sound and lists sources such as vehicles, industries, and recreational activities. Noise has properties of loudness measured in decibels and frequency measured in Hertz. Exposure to noise can cause auditory effects like hearing loss as well as non-auditory effects such as annoyance, decreased work efficiency, and health issues. Controlling noise involves city planning, vehicle and building regulations, worker protections, and education programs.

1. NOISENOISE
KIRTHANA MUTHU
III BDS
DEPARTENT OF PUBLIC HEALTH DENTISTRY

2. CONTENTS
• INTRODUCTION
• DEFINITIONS
• SOURCES OF NOISE
• PROPERTIES OF NOISE
• EFFECTS OF NOISE EXPOSURE
• CONTROL OF NOISE
• SUMMARY

3. INTRODUCTION
• The word noise originates from Latin word
'noxia' meaning hurt / injury.

4. DEFINITIONS
• Unwanted sound ----> too subjective
- one man's sound may be another man's
noise
• Better definition : Wrong sound in the
wrong place at the wrong time

5. SOURCES OF NOISE
• Many & varied
Ex:
 Automobiles, factories,
industries, aircrafts.
 Railway junctions, traffic
round-abouts, bus
terminuse , airports.
 Use of pressure horns,
recreational noises of
loudspeakers with full
volume during festivities.
 Domestic noises: radios,
transistors,T.V sets.

6. PROPERTIES OF NOISE
• 2 important properties :
 Loudness
Frequency

7. LOUDNESS
• Depends upon the amplititude of vibrations
which initiated the noise.
• Unit : decibels (dB)
• Reference sound pressure = smallest
distinguishable noise
- 0.0002 microbar or dynes/cm2
- 1 dynes = 1/106 th of atmospheric
pressure

9. FREQUENCY
• Number of cycles per
unit time.
• Unit : Hertz (Hz) , 1
Hz is equal to one
wave per second
• Range audible to
human:20-20000 Hz
• < 20 Hz - infraudible
• >20000 Hz -ultrasonic

10. EFFECTS OF NOISE EXPOSURE
• AUDITORY EFFECTS
i. Auditory Fatigue
- appears in the 90 dB region & greatest in
4000 Hz.
- Side effects : whistling & buzzing in the
ears

11. ii. Deafness/Hearing loss
- maybe temporary / premanent
Temporary Hearing Loss:
- results from a specific exposure to noise
- the disability disappears after a period of
time upto 24 hours following the exposure
- occurs in frequency : 4000-6000 Hz

12. Permanent Hearing Loss
- repeated or continous exposure to noise
around 100 dB.
- In this, inner ear damage occurs
- Exposure to noise > 160 dB may rupture
the tympanic membrane & cause
permanent loss of hearing

13. • NON-AUDITORY EFFECTS
i. Annoyance
- Primarily a psychological effect
- Neurotic people are more sensitive to
noise than balanced people
- Workmen exposed to higher intensity of
noise in occupational capacities are often
irritated, short tempered & impatient.

14. ii. Efficiency
- Low level of noise--->better mental
concentration---> increase work output
iii. Physiological changes
- Rise in BP, rise in HR, rise in itracranial
pressure, increase in sweating
- Interferences with sleep
- Causes visual disturbances

15. iv. Interference with speech
- Frequencies causing most
disturbances to speech
commuication : 300-500 Hz.
- This is commonly produced
by road & air traffic.
- For good speech intelligibility,
it is considered that speech
sound level must exceed the
SIL (Speech Interference
Ievel) by 12 dB.

16. v. Economic loss
- The potential cause of
noise induced hearing
loss to industry is
quite great.

17. CONTROL OF NOISE
• CAREFUL PLANNING
OF CITIES
- Division of the city into
zones with separation of
ares concerned with
industry & transport.
- The separation of
residential areas from the
main streets by means of
wide green belts.
- Widening of main streets
to reduce the noise
penetration into the
dwellings.

18. • CONTROL OF
VEHICLES
- Heavy vehicles
should not be routed
into narrow streets.
- Vehicular traffic in
residential areas
should be reduced.
- Indiscrimate blowing
of the horn & use of
pressure horn should
be prohibited.

19. • TO IMPROVE
ACOUSTIC
INSULATION OF
BUILDING
- The best arrangement is
the construction of
detached buildings rather
than a single large
building or one that is
continous
- Buildings should be
sound-proof where
necessary

20. • PROTECTION OF
EXPOSED PERSON
- For workers consistently
exposed to noise > 85 dB
in the frequence bands >
150 Hz.
- Workers must be
regularly rotated to from
noisy ares to
comparatively quiet posts
in factories.
- Periodical radiogram
check-ups.
- Use of ear plugs, ear
muffs.

21. • LEGISLATION
- Workers have right to
claim compensation if
they have suffered a loss
of ability to understand
speech.
• EDUCATION
- Education through all
available media is
needed to highlight the
importance of noise as a
community hazard.

22. SUMMARY
• Man is living in a increasingly noisy
environment. The 20th century has been
described as the "Century of Noise".Noise
has become a very important stress factor
in the environment of man. Hence,
participation of people in noise abatement
programmes is necessary to combat this
problem.

23. REFERENCES
• PARK, 22 EDITION