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Distance Attenuation Calculator

Calculate sound pressure level (SPL dB), Doppler frequency shift, speed of sound in air/water/solids, and room reverberation time (RT60) for distance attenuation.

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Input Acoustic Parameters

Enter frequency, temperature, sound intensity, or distance.

Sound Frequency f (Hz)

Air Temperature T (°C)

Calculated Sound Speed / Wavelength

343.00 m/s

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Speed of Sound in Air

In dry air at 20°C (68°F), the speed of sound is c ≈ 343 m/s (1,125 ft/s or 767 mph). It increases by ~0.6 m/s for every 1°C increase in temperature.

Calculation Methodology & Details

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Formula

Speed of Sound in Air: c = 331.3 × √(1 + T / 273.15) Sound Pressure Level: SPL = 20 × log₁₀(p / p₀) dB (p₀ = 20 μPa) Doppler Shift: f_observed = f_source × (c + v_observer) / (c - v_source) Sabine RT60: RT60 = 0.161 × V / A

Applies acoustic wave dynamics, decibel logarithmic scales, Doppler effect shifts, and Sabine architectural acoustics.

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Important Disclaimer

Calculations assume ideal gas sound propagation without non-linear atmospheric absorption or humidity dispersion at extreme frequencies.

How to Calculate Step-by-Step

Follow these steps to complete the calculation:

Step 1

Input sound frequency f (Hz) or source/observer velocities v (m/s).

Step 2

Specify air temperature T (°C), acoustic medium density ρ (kg/m³), or distance d (meters).

Step 3

View speed of sound c (m/s), sound pressure level (dB SPL), sound wavelength λ (meters), or Doppler shifted pitch.

Detailed Insights & Expert Guide

ℹ️ About this Calculation

The Distance Attenuation Calculator calculates sound pressure level (dB), Doppler effect frequency shift, room reverberation time (RT60), Helmholtz resonator tuning, and speed of sound in solids/fluids.

Variable Glossary

Input

Sound Intensity (I)

Sound power per unit area measured in Watts per square meter (W/m²).

Parameter

Decibel (dB SPL)

Logarithmic ratio unit comparing sound pressure to human threshold of hearing (20 μPa).

FAQ

How does the Doppler Effect change frequency?

When a sound source approaches an observer, wave crests compress, shifting observed frequency higher. As the source moves away, wave crests spread, shifting observed pitch lower.

What is room reverberation time (RT60)?

RT60 is the time required for sound pressure level to decay by 60 dB after the sound source stops. Optimal RT60 for speech is ~0.5s; for orchestral music, ~1.8s–2.2s.

How does decibel addition work?

Because decibels are logarithmic, adding two identical 80 dB sound sources results in 83 dB (a +3 dB increase), NOT 160 dB. Formula: L_total = 10 × log₁₀(10^(L1/10) + 10^(L2/10)).