The Sound Level, or Sound Pressure Level, is a measure of the 'level' of sound that is messured in [[Bel|Bels]] $\pu b$. $\huge B = \log_{10}\pa{\frac{I}{I_{0}}} $ $\huge B = \log_{10}\pa{\frac{P_{\text{RMS}}}{P_{0}}} $ Where $I$ and $P$ refer to the [[Wave Intensity]] and [[Pressure|Pressure]], and $P_{\text{RMS}}$ is the [[Root Mean Squared]] of the [[Pressure]]. The more commonly used measure however is the [[Bel|Decibel]] $\pu{db}$, defined as $1\pu{ db }=10\pu{ b }$ $\huge \begin{align} \text{Db }= 10\log_{10}\pa{\frac{I}{I_{0}}}= 10\log_{10}\pa{\frac{P_{\text{RMS}}}{P_{0}}} \end{align}$