Analyze sound power, intensity, and level across distance. Compare output with directivity and loss inputs. Visualize decay trends for smarter acoustic design choices today.
Use watts for direct source power. Use dB when the sound power level is already known.
This sample curve uses 0.1 W, Q = 1, and no extra losses.
| Case | Power (W) | Distance (m) | Q | Air Loss (dB/m) | Extra Loss (dB) | Power Level (dB) | Estimated SPL (dB) |
|---|---|---|---|---|---|---|---|
| 1 | 0.01 | 1.00 | 1.00 | 0.00 | 0.00 | 100.00 | 89.17 |
| 2 | 0.05 | 2.00 | 1.00 | 0.00 | 0.00 | 106.99 | 90.14 |
| 3 | 0.10 | 5.00 | 1.00 | 0.00 | 0.00 | 110.00 | 85.19 |
| 4 | 0.50 | 10.00 | 2.00 | 0.01 | 0.00 | 116.99 | 89.07 |
| 5 | 1.00 | 20.00 | 4.00 | 0.02 | 1.00 | 120.00 | 87.77 |
1) Lw = 10 log10(P / 10-12)
Converts sound power in watts into sound power level.
2) P = 10-12 × 10(Lw / 10)
Converts sound power level back into watts.
3) I(r) = [P × Q / (4πr2)] × 10-(αr + Lextra)/10
Calculates sound intensity at distance r.
4) SPL ≈ 20 log10(prms / 20 μPa)
Uses pressure derived from intensity in air.
5) Spreading Loss = 10 log10[(4πr2) / Q]
Shows geometric decay from distance and directivity.
This page assumes free-field propagation, spherical spreading, and approximate air impedance near room conditions. Strong reflections, complex rooms, and unusual weather can change real measurements.
Sound power is the total acoustic energy emitted by a source. It belongs to the source itself, not to the listener position.
In free-field conditions, level drops as distance increases. Doubling distance usually reduces level by about 6 dB before added air losses.
Q describes how strongly a source focuses sound. A larger Q sends more energy into a smaller region, raising level in that direction.
No. Sound power is emitted by the source. Sound pressure depends on where you measure, plus distance, reflections, and attenuation.
Use dB when a manufacturer lists sound power level directly. Use watts when the acoustic output is known as physical power.
Sometimes. Short indoor paths may have little air loss, but barriers, ducting, enclosures, and absorptive materials can still reduce level noticeably.
The graph drops because sound energy spreads over a larger area with distance. Added absorption and extra losses steepen the decline.
No. They are engineering estimates. Real spaces can differ because of reflections, humidity, source directivity patterns, shielding, and measurement technique.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.