‘UNWANTED SOUND’

REGULAR AND PROLONGED OR SUDDEN

EXPOSURE TO ANY UNPLEASANT

DAMAGING & IRRITATING NOISE ABOVE

A CERTAIN LEVEL WHICH WILL HARM

HUMANS, WILDLIFE OR ENVIRONMENT IN

SOME WAY.

VEHICULAR – RAILWAYS, MOTOR

TRANSPORT, AIRCRAFTS ETC.

INDUSTRIAL – MACHINERIES, BLASTING &

DRLLING OPERATIONS, GENERATORS,

IRON FOUNDARIES

RECREATIONAL – LOUDSPEAKERS,

BURSTING OF CRACKERS, LOUD VOLUME

OF T.V. SETS ETC.

LOUDNESS – (INTENSITY) DEPENDS ON AMPLITUDE OF VIBRATIONS.

MEASURED IN DECIBELS (dB)

MORE IMP. – PERCEIVED INTENSITY BY HUMAN EAR

CURVE A MEASURES SUBJECTIVE EFFECTS OF SOUND

SAFE LIMIT FOR AMBIENT SOUND (CPCB)

RESIDENTIAL – 55 dB

COMMERCIAL – 65 dB

ISO – 90 dB AS SAFE LIMIT

SOURCE OF NOISE SOUND LEVEL (d B)

WHISPERING 10

SPEECH 2-3 PEOPLE 73

SPEECH ON RADIO 80

MUSIC ON RADIO 85

CHILDREN SHOUTING 79

CHILDREN CRYING 80

VACUUM CLEANER 76

PIANO 86

JET TAKE-OFF 150

FREQUENCY – 20- 20,000 Hz CAN BE HEARD BY

HUMAN EAR

PHON – PSYCHO ACOUSTIC INDEX OF LOUDNESS

- TAKES INTENSITY & FREQUENCY INTO

CONSIDERATION

AUDITORY EFFECTS

1. AUDITORY FATGUE – APPEARS IN 90 dB

REGION & MAX. AT 4000 Hz.

2. DEAFNESS – (NOISE INDUCED HEARING

LOSS)

TEMPORARY

PERMANENT

OTITIC BLAST INJURY - RUPTURE OF TYMPANIC MEMBRANE

NON AUDITORY EFFECTS

1. INTERFERENCE WITH SPEECH

2. ANNOYANCE

3. PHYSIOLOGICAL CHANGES – RISE IN BP,

HEART RATE, ICP, BREATHING RATE

4. LOSS OF EFFICIENCY

ENGINEERING MEASURES

LEGISLATION

PERSONAL PROTECTIVE MEASURES

PLANNING OF CITIES

ACOUSTIC INSULATION OF BUILDINGS

SETTING UP OF INDUSTRIES IN EARMARKED

AREAS

CONTROL OF VEHICLES

BAN ON BURSTING OF CRACKERS FROM

10 p.m. – 6 a.m.

BAN ON USE OF SOUND EMITTING

INSTRUMENTS OR SOUND AMPLIFIERS AT

NIGHT EXCEPT IN PUBLIC EMERGENCY

NIHL – INCLUDED IN FACTORIES ACT & IS

COMPENSABLE

USE OF EAR PLUGS, EAR MUFFS

PERIODIC AUDIOGRAMS & CHECK UPS

HEALTH EDUCATION