• All sounds that are distracting, annoying, or harmful to
everyday activities such as
work, rest, entertainment, study and so forth are regarded
as noises. In fact, any sound judged by the recipient as
undesirable can be considered as a noise.
• Noise health effects are the health consequences of
elevated sound levels.
• Elevated workplace or other noise can cause hearing
impairment, hypertension, ischemic heart
disease, annoyance, and sleep disturbance.
• Changes in the immune system and birth defects have
been attributed to noise exposure.
• Although some presbycusis may occur naturally with
age, in many developed nations the cumulative impact of
noise is sufficient to impair the hearing of a large fraction
of the population over the course of a lifetime.
• Noise exposure also has been known to induce
tinnitus, hypertension, vasoconstriction, and other
cardiovascular adverse effects.
• Beyond these effects, elevated noise levels can create
stress, increase workplace accident rates, as well as
stimulating aggression and other anti-social behaviours.
• The most significant causes are vehicle and aircraft
noise, prolonged exposure to loud music, and industrial
• Firecrackers may upset domestic and wild animals or
• The most common noise-traumatized persons are those
exposed to military conflicts, but often loud groups of
people can trigger complaints and other behaviours about
• One in five Europeans is regularly exposed to sound
levels at night that could significantly damage health.
• Noise also is a threat to marine and terrestrial
Effects of noise
• Age-related (presbycusis)
• Hearing loss
• Cardio-vascular effects
• Child physical development
• Cognitive development
• Whether or not a sound is undesired by a person will
depend on a number of factors, e.g.
(d) Variation with time.
(e) Time of occurrence.
(f) Information content.
(g) Origin of the sound.
(h) Recipient's state of mind and temperament.
(i) Background noise level.
general, the effects of noises are:
• Exposure to high noise levels causes hearing loss. This
loss of hearing may be temporary, permanent, or a
combination of both. Temporary hearing loss, also called
Temporary Threshold Shift (TTS), results from exposure
to short-term loud noises. As time passes, temporary
hearing loss will disappear. However, if the human ear is
not given the opportunity to recover, permanent hearing
loss or Permanent Threshold Shift (PTS) will result
because of the destruction of parts of the ear. Permanent
hearing losses cannot be treated.
Other Health Effects
• People living or working in noisy environments develop
the habit of shouting; some are stressed and become
irritable. There is evidence that noise can lead to
psychiatric disorders. When human beings are exposed to
high noise levels, the blood vessels constrict and muscles
(c) Speech Interference & masking
• One cannot effectively use speech communication in an
environment in which the background noise level is too
high. Sometimes, the masking of warning shouts by
background noise is responsible for industrial accidents.
Nevertheless, a reasonable level of background noise is
sometimes useful, e.g.
(i) the masking of speech so that speech privacy in large
areas is maintained.
(ii) minimizing the effect of intruding noises.
(iii) maintaining the sanity of human beings: human
beings cannot tolerate absolute silence in a perfect
soundproof environment for any length of time.
Effects of Noise on wildlife
• Hearing impairment and loss
• Disturbance and stress
• Psychological suffering
Noise Permissible Exposure Limits (PEL)
Utilize administrative or engineering controls when
sound levels exceed Noise Permissible Exposure
Levels e.g. 8 hours permitted duration per workday
for 90 dB sound level.
Provide hearing protectors if above controls fail to
reduce sound levels within Permissible Exposure
Impulsive or impact noise should not exceed 140 dB.
•Controlling or attenuating at its source
•Controlling or attenuating along its path
•Controlling or attenuating at the receiver
• Administrative Control
• Engineering Control
• Personal Protective Equipment ( hearing protective
• Operate noisy equipment on second or third shifts.
• Rotate employees through high-noise areas.
• Modify existing machinery.
• Place noise limit specs. on new equip.
• Maintain equip. in good condition.
• Use noise control when installed.
• Reporting noisy equip. to supervisor for repair.
• Reduce noise at the source.
• Interrupt the noise path.
• Reduce reverberation and structural vibration.
Personal Protective Equipment (Hearing
Protection Devices - HPD)
• Employers shall provide to employees exposed to
8 hr TWA of 85 dB at no cost.
• Employers shall ensure being worn:
• by employees exposed to 8 hr TWA of 90dB or greater
• by employees exposed to 8 hr TWA of 85dB or greater
• Whose baseline audiogram has not been established
• Who have experienced a threshold shift
Hearing Protection Device (HPD)
HPD must reduce employee noise exposure
below PEL e.g. below 8 hr TWA of 90 dB.
Employees with standard threshold shift
(STS), HPD must reduce employees noise
exposure below an 8 hr TWA of 85 dB.
Noise Control Methods
• Acoustical materials
• Acoustical enclosures and barrier
• Silencers and mufflers
• Reverberation control
• Vibration control
Noise is undesirably connected with our day to day life. It’s
a part in our economic growth .There is no way to get rid of
this noise completely from our life . But we can manage to
reduce and restrict them to some extent by following the
few measures mentioned above.