Sound Pressure Level (SPL)
Sound Pressure Level (SPL) is the logarithmic measure of the effective pressure of a sound relative to a reference value of 20 micropascals, expressed in decibels (dB). It is the most commonly measured quantity in acoustics and forms the basis of most noise regulations. SPL is defined in IEC 61672-1 and relates to the human threshold of hearing at 1 kHz. Typical values range from 0 dB (hearing threshold) to 130 dB (threshold of pain). In room acoustics, SPL measurements are used for background noise surveys, noise criteria assessments (NR/NC curves), and speech level predictions. A-weighted SPL (dB(A)) is the most common single-number descriptor in building regulations worldwide.
Formula
SPL = 20 × log₁₀(p / p₀)Unit
Expressed in dB
Related Standards
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