Basic Knowledge and Fun Facts of AcousticsAcoustics 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 21°C (70°F) 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. |