Noise Exposure - Permissible Levels and Duration - Exposure to noise should be controlled so that it is less than a maximum combination of exposure level and duration.Noise - Acceptable dB A Level - Acceptable noise - dB A - level at typical common locations.NC - the Noise Criterion - Noise Criterion - NC - level is a standard uesd to describe the relative loudness of a space within a range of frequencies.Maximum Sound Pressure Levels in Rooms - Maximum recommended sound pressure levels in rooms like kindergartens, auditoriums, libraries, cinemas and more.Decibel A, B and C - Sound pressure filters that compensates for the hearing sensed by the human ear.Decibel - Logarithmic unit used to describe ratios of signal levels - like power or intensity - to a reference level.Noise and Attenuation - Noise is usually defined as unwanted sound - noise, noise generation, silencers and attenuation in HVAC systems.Physiology - Human physiology, air quality and comfort temperatures, activity and metabolic rates, health effects of carbon monoxide and more.Acoustics - Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.
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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