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Sound pressure level (SPL)
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Sound intensity is expresses the pressure caused by a sound wave and is indicated by sound pressure level. The unit of measurement is the decibel (dB SPL)
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dB Scale
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A logarithmic scale to measure sound pressure level
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dBA
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To measure noise, A-weighted SPL (dBA) can be used. In contrast to SPL which represents a physical dimension, A-weighted SPL represents a perceptual dimension. The dB SPL will be different from dBA for different for different frequencies as low frequency sounds and high frequency sounds tend to be less loud than mid-frequency sounds
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L
Aeq
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This refers to the average level of sound pressure within a certain time period with the A-filter used for frequency weighting. The A-filter is a frequency-weighting of sound pressure levels that mimics the sensitivity of the auditory system of humans (eg, low-frequency sounds contribute little to the A-weighted dB level)
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