Date post: | 19-Jun-2015 |
Category: |
Education |
Upload: | ravi-kaushal |
View: | 66 times |
Download: | 0 times |
NOISE CONTROL AND ACOUSTICS
NOISE CONTROL
• set of strategies to reduce noise pollution or to reduce the impact of noise, whether outdoors or indoors.
• The main areas of noise mitigation are
machines
transportation systems
Air craft
trains
motor vehicles
Noise Criteria In Buildings
Room Criteria (RC)
Noise Criteria (NC)
The Speech Interference Level (SIL)
ROOM CRITERIA (background noise in a building over the frequency range 16 Hz to 4000 Hz)
ROOM CRITERIA cont….
NOISE CRITERIA
• Noise Criterion - NC - were established in U.S. for rating indoor noise, noise from air-conditioning equipment etc.
• The method consists of a set of criteria curves extending from 63 to 8000 Hz, and a tangency rating procedure
NOISE CRITERIA cont….
NOISE CRITERIA cont….
Speech Interference Level (SIL)
• Speech Interference Level (SIL) is an acoustical parameter calculated from sound pressure levels measured in octave bands.
• sound pressure levels in three or four octave bands in the 500 Hz - 4 kHz frequency range
sound
vibration
Sound
•A disturbance in an elastic medium resulting in an audible sensation. Noise is by definition “unwanted sound”.
Vibration
• A disturbance in a solid elastic medium which may produce a detectable motion
UNITS OF ACOUSTICS
• The basic unit of level in acoustics is the “decibel” (abbreviated dB). In acoustics, the term “level” is used to designated that the quantity is referred to some reference value, which is either stated or implied.