In the context of noise pollution, SPL is the sound pressure level in decibels (dB). The relationship between SPL, the root mean square $\text{(rms)}$ sound pressure $p$ $\text {,and the reference (hearing threshold) pressure } p_{0} \text { is }$ expressed as ___________.
- $\mathrm{SPL}=20 \times \log _{10} \frac{p}{p_{0}}$
- $\mathrm{SPL}=20 \times \log _{10} \frac{p_{0}}{p}$
- $\mathrm{SPL}=20-\log _{10} \frac{p}{p_{0}}$
- $\mathrm{SPL}=20+\log _{10} \frac{p}{p_{0}}$
