Speed Sound

Overview

Engineering reference data for Speed Sound in acoustics.

Key Formulas

Speed of Sound

$c = \sqrt{\gamma R T}$

Speed of sound in an ideal gas.

Sound Level

$L = 10 \log_{10}(I/I_0)$

Decibel level.

Wavelength

$\lambda = c / f$

Wavelength = speed / frequency.

Variables

Symbol	Description	Unit
$c$	Speed of sound	m/s
$L$	Sound level	dB
$\lambda$	Wavelength	m
$f$	Frequency	Hz

Examples of Speed of Sound Calculations

In Air (Ideal Gas)

Using $c = \sqrt{k R T}$, where $k = 1.4$ and $R = 286.9 \, \text{J/(kg K)}$ for air:

• At 0°C (273.15 K): $c = \sqrt{1.4 \times 286.9 \times 273.15} = 331.2 \, \text{m/s}$
• At 20°C (293.15 K): $c = \sqrt{1.4 \times 286.9 \times 293.15} = 343.1 \, \text{m/s}$

In Water

Using $c = \sqrt{\frac{K}{\rho}}$:

For water at 1

Interactive Charts

References

• Original Source