Acoustics - Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.If the pressure is doubled the sound pressure level is increased with 6 dB (20 log (2)).
P ref = 2 10 -5 - reference sound pressure (Pa) The Sound Pressure Level in decibel can be expressed as The SI-unit for the Sound Pressure is N/m 2 or Pa. The sound pressure is the force (N) of a sound on a surface area (m 2) perpendicular to the direction of the sound. I ref = 10 -12 - reference sound intensity (W/m 2) Sound Pressure Level The Sound Intensity Level can be expressed as: The SI-unit for Sound Intensity is W/m 2. Sound intensity is the ratio acoustic or sound power to area. The loudest sound power generally possible to encounter is that of a jet aircraft with a sound power of 10 5 W - 170 dB.The lowest sound power persons with excellent hearing can discern is about 10 -12 W - defined as 0 dB in the decibel scale.Sound power can more practically be expressed in a logarithmic scale named Sound Power Level as the ratio of sound power to the sound power at the threshold of hearing - 10 -12 W : Sound power is the energy rate - the energy of sound per unit of time (J/s, W in SI-units) from a sound source. Decibel is a logarithmic unit used to describe ratios of physical values like - like power, sound pressure, voltage, intensity and more.
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