Sound Pressure Level Calculator
Enter sound pressure p in Pa to compute the sound pressure level L=20·log₁₀(p/2e-5) in dB. p=0.632 Pa → L≈90 dB. Reference p₀=20 µPa. Complements decibel and frequency tools.
Input Data
Results
At a glance:The sound pressure level L=20·log₁₀(p/p₀), with reference p₀=20 µPa (2×10⁻⁵ Pa), the standard dB measure of sound pressure — the actual pressure fluctuation of a sound wave. It complements the decibel and frequency calculators. Term by term: p is the RMS sound pressure (Pa); p₀ the reference (20 µPa in air, the 1 kHz hearing threshold). The 20·log scale compresses the huge human range (from 20 µPa to 20 Pa, 10⁶×) into 0–120 dB. Example: p=0.632 Pa → L=20·log₁₀(0.632/2e-5)=20·log₁₀(31600)≈90 dB. History: the decibel was defined in 1920s telephone engineering; the logarithmic scale follows the Weber–Fechner law of sensation. Classic examples: 20 µPa→0 dB (threshold); 0.632 Pa→90 dB; 20 Pa→120 dB (pain). Applications: (1) noise assessment; (2) room and building acoustics; (3) audio calibration; (4) environmental noise monitoring.
Formula
L = 20·log₁₀(p / 2e-5) dB
p sound pressure (Pa), reference 2e-5 Pa (20 µPa)
Pressure ×10 → +20 dB; ×2 → +6 dB
$$L = 20\log_{10}\!\frac{p}{2\times 10^{-5}}$$How to Use
- Enter the sound pressure p (Pa).
- The tool gives the SPL in dB.
Case Studies
0.632 Pa → 90 dB
20·log₁₀(0.632/2e-5) ≈ 90 dB — a loud but common level (lawnmower, truck).
FAQ
How is this different from decibel?
Decibel is general; this one is specifically sound pressure level (SPL).
Where is it used?
Noise assessment and audio calibration.
Precision?
2 decimal places.
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.