itft--acoustics

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.