\[L_p = 20\log_{10}\left(\frac{p}{p_0}\right)\]
Variables
Lpsound pressure level (dB)
proot mean square sound pressure (Pa)
p0reference sound pressure (Pa)
Description
What is this formula?
The Sound Pressure Level formula expresses the effective sound pressure relative to a reference pressure using a logarithmic decibel scale. It is the most commonly used acoustic measurement because sound pressure can be measured directly with microphones.
When to use it
Use this formula when measuring environmental noise, evaluating workplace sound exposure, testing audio equipment, or analyzing acoustic systems.
Example
Given:
p = 0.2 Pa
p0 = 2×10^-5 Pa
Formula:
Lp = 20 log10(p/p0)
Substitution:
Lp = 20 log10(0.2/(2×10^-5))
Lp = 20 log10(10000)
Lp = 80 dB
Result:
Lp = 80 dB
Applications
Noise monitoring.
Acoustic engineering.
Audio system testing.
Occupational safety.
Environmental acoustics.