Page 118 - GRIHA Manual Volume IV - Introduction to National Rating System
P. 118
Building planning and construction 109
CRIteRIon 29
ACCeptAble outdooR And
IndooR noIse levels
Introduction
There are several sources of noise that contribute to both indoor and outdoor noise pollution.
Community noise (also called environmental noise, residential noise or domestic noise) is defined
as noise emitted from all sources except noise at the industrial workplace. Main sources of
community noise include road, rail, and air traffic; industries; construction and public work; and the
neighbourhood.
The main indoor sources of noise are ventilation systems, office machines, home appliances,
and neighbours. Typical neighbourhood noise comes from premises and installations related to the
catering trade (restaurant, cafeterias, discotheques, and so on); from live or recorded music; sport
events including motor sports; playgrounds; car parks; and domestic animals, such as barking dogs.
The difference between sound and noise is often subjective and a matter of personal opinion.
However, the unwanted sound can damage physiological and psychological health. Interference
with communication; noise-induced hearing loss; sleep disturbance effects; cardiovascular and
psycho-physiological effects; performance reduction effects; annoyance responses; and effects
on social behaviour are some of the impacts of noise pollution. It can also cause annoyance and
aggression, hypertension, high stress levels, tinnitus, and other harmful effects. Furthermore,
stress and hypertension are the leading causes of health problems, whereas tinnitus can lead to
forgetfulness, severe depression, and at times, panic attacks. Chronic exposure to noise may also
cause noise-induced hearing loss.
Solution
While doing acoustical planning the following two key material properties are analysed.
1. Noise Reduction Coefficient (NRC): NRC reflects the ability of a material to absorb sound.
NRC provides information on the absorptive abilities of a material, when referring to mid-
frequency sound and does not reflect on the sound barrier effect of materials. It is usually
denoted by decimal ranging from 0, which means that the material is perfectly reflective,
to 1, which means that the material is perfectly absorptive and absorbs all sound that falls
on it.
2. Sound Transmission Class (STC): STC reflects the barrier effect of a material/assembly. It
is also represented as a single number. The higher the STC number for a material, the
greater is its sound barrier effect. The STC of a partition can be increased by increasing the
mass (weight/thickness) of the partition/wall, adding air gaps in the partitions/walls, and
adding a sound absorbing material to further reduce sound transmission through the
partition/wall.
CRIteRIon 29
ACCeptAble outdooR And
IndooR noIse levels
Introduction
There are several sources of noise that contribute to both indoor and outdoor noise pollution.
Community noise (also called environmental noise, residential noise or domestic noise) is defined
as noise emitted from all sources except noise at the industrial workplace. Main sources of
community noise include road, rail, and air traffic; industries; construction and public work; and the
neighbourhood.
The main indoor sources of noise are ventilation systems, office machines, home appliances,
and neighbours. Typical neighbourhood noise comes from premises and installations related to the
catering trade (restaurant, cafeterias, discotheques, and so on); from live or recorded music; sport
events including motor sports; playgrounds; car parks; and domestic animals, such as barking dogs.
The difference between sound and noise is often subjective and a matter of personal opinion.
However, the unwanted sound can damage physiological and psychological health. Interference
with communication; noise-induced hearing loss; sleep disturbance effects; cardiovascular and
psycho-physiological effects; performance reduction effects; annoyance responses; and effects
on social behaviour are some of the impacts of noise pollution. It can also cause annoyance and
aggression, hypertension, high stress levels, tinnitus, and other harmful effects. Furthermore,
stress and hypertension are the leading causes of health problems, whereas tinnitus can lead to
forgetfulness, severe depression, and at times, panic attacks. Chronic exposure to noise may also
cause noise-induced hearing loss.
Solution
While doing acoustical planning the following two key material properties are analysed.
1. Noise Reduction Coefficient (NRC): NRC reflects the ability of a material to absorb sound.
NRC provides information on the absorptive abilities of a material, when referring to mid-
frequency sound and does not reflect on the sound barrier effect of materials. It is usually
denoted by decimal ranging from 0, which means that the material is perfectly reflective,
to 1, which means that the material is perfectly absorptive and absorbs all sound that falls
on it.
2. Sound Transmission Class (STC): STC reflects the barrier effect of a material/assembly. It
is also represented as a single number. The higher the STC number for a material, the
greater is its sound barrier effect. The STC of a partition can be increased by increasing the
mass (weight/thickness) of the partition/wall, adding air gaps in the partitions/walls, and
adding a sound absorbing material to further reduce sound transmission through the
partition/wall.
