How it propagates

The type of source;

• Point source
• Line source
• Plane source

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Point sources

• Sound sources that generates sound energy in spheric waves or like spheric waves are called point sources.
• The sound intensity “I” at a distance “r” generated from a point source whose acoustic power W is given by 

                    I= W/4Пr²

since the total energy which passes through a sphere of surface area “4 Пr²” is W.

Intensity is inversely proportional to the square of distance for point source
 
Attenuation value (dB) = 10 log n²
 
n: ratio of distance
 
n = r2/r1
 
r1: initial distance from the source
r2: altered distance from the source

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Line sources 

• Sound sources that generates sound energy in cylindrical waves or like cylindrical waves are called line sources.

• When there are many sound sources in a row such as vehicles on a motorway, they are considered as a line source.
• The sound intensity “I” at a distance “r” generated from a line source whose acoustic power W is given by

                        I= W/2Пr

Intensity is inversely proportional to the distance for line source

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Plane sources

• Sound sources that generates sound energy in plane waves or like plane waves are called plane sources.

• When there are many sound sources on a plane surface such as children playing at a park, they create a plane source.
• Because the area of the generated sound will be the same at propagation by plane waves,

Theorectically the sound energy will not change with distance for plane sources

• Noise and its impact
• Basic information on acoustics
  • Where it borns
  • Where it propagates
  • How it propagates
• Acoustic comfort