Advanced Sound Propagation Calculator

Analyze spreading, absorption, wind effects, and travel time. Adjust geometry, barriers, humidity, and reference levels. Visualize attenuation trends with exports, formulas, examples, and guidance.

Calculator Inputs

Source SPL at Reference (dB)

Reference Distance (m)

Target Distance (m)

Frequency (Hz)

Air Temperature (°C)

Relative Humidity (%)

Air Pressure (kPa)

Wind Speed (m/s)

Wind Angle to Path (°)

Barrier Loss (dB)

Ground Adjustment (dB)

Directivity Gain (dB)

Spreading Model

Absorption Mode

Custom Absorption (dB/m)

Propagation Graph

This chart plots predicted sound level against distance using the current inputs.

Example Data Table

Case	Source SPL (dB)	Reference (m)	Target (m)	Frequency (Hz)	Temp (°C)	Humidity (%)	Model
Open Field A	100	1	50	1000	20	50	Spherical
Warehouse Path	92	1	25	500	24	60	Cylindrical
Barrier Scenario	105	1	80	2000	18	40	Spherical

Formula Used

1. Speed of sound
c = 331.3 + 0.606 × T

2. Wavelength
λ = c / f

3. Wind-adjusted propagation speed
c_effective = c + v_wind × cos(θ)

4. Geometric spreading loss
Spherical: L_spread = 20 × log₁₀(r / r_ref)
Cylindrical: L_spread = 10 × log₁₀(r / r_ref)

5. Atmospheric absorption loss
L_atm = α × (r - r_ref)

6. Received level
L_received = L_source - L_spread - L_atm - L_barrier + L_ground + L_directivity

The automatic absorption coefficient uses a standard air-absorption estimate based on frequency, temperature, humidity, and pressure.

How to Use This Calculator

Enter the source sound level measured at the reference distance.
Set the target distance where you want the received level.
Add the frequency, temperature, humidity, and air pressure.
Choose spherical or cylindrical spreading for your scenario.
Apply barrier loss, ground adjustment, and directivity gain if needed.
Keep automatic absorption for standard use, or enter a custom coefficient.
Press the calculate button to show results above the form.
Use the CSV or PDF buttons to export the current calculation summary.

Frequently Asked Questions

1. What does this sound propagation calculator estimate?

It estimates received sound level at a target distance. It also calculates wavelength, travel time, speed of sound, air absorption loss, and net attenuation after environmental and path adjustments.

2. When should I choose spherical spreading?

Choose spherical spreading for open environments where sound radiates outward in three dimensions. Outdoor sources, point emitters, and many free-field cases are commonly modeled this way.

3. When is cylindrical spreading more appropriate?

Cylindrical spreading is useful where reflections or confinement make sound decay more slowly with distance. Long corridors, tunnels, and some industrial aisles can resemble this behavior.

4. Why do temperature and humidity matter?

They affect both the speed of sound and atmospheric absorption. Higher frequency sound especially changes with air conditions, so environmental inputs improve the realism of long-path predictions.

5. What is the barrier loss field for?

Use barrier loss to represent shielding from walls, enclosures, berms, or acoustic screens. It subtracts directly from the received level after other propagation terms are considered.

6. What does ground adjustment mean here?

Ground adjustment lets you apply a practical correction for surface interaction. Depending on conditions, ground can reduce or reinforce certain frequencies and propagation paths.

7. Should I use auto or custom absorption?

Use auto for standard engineering estimates based on current environmental inputs. Use custom when you already know the attenuation coefficient from measurements, standards, or project specifications.

8. Can I export the calculated results?

Yes. The page includes CSV export for spreadsheet use and PDF export for reporting. Both options use the latest successful calculation displayed above the form.