Basic Knowledge and Fun Facts of Acoustics

Acoustics n.
1. (used with a sing. verb) The scientific study of sound, especially of its generation, transmission, and reception.
2. (used with a pl. verb) The total effect of sound, especially as produced in an enclosed space.

Noise n.
1. Sound, or a sound that is loud, unpleasant, unexpected, or unwanted.
2. Sound, or any kind of sound.
3. A loud outcry or commotion.
4. (Physics) A disturbance, especially a random and persistent disturbance, that obscures or reduces the clarity of a signal.

Decibel n. (literally meaning ten "Bels")
1. The unit of measure used to describe a sound level. Named for Alexander Graham Bell, inventor of the telephone and advocate for the hearing impaired.
2. Sound Pressure Level = 20 x log ( Pacoustic / P0) Where P0 = 20 micro-pascals (approximate threshold of hearing)

Speed of Sound:
At 21C (70F) the speed of sound in air is 344 m/s, or 1129 ft/s. At freezing, the speed is 331 m/s, or 1087 ft/s.

The formula for the dependence on temperature is:

Where T is the degrees in Celcius and V is the speed of sound in meters per second.




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