How fast does sound travel through that?
Sound travels four times faster in water than air and fifteen times faster in steel. Stiffness raises it; density lowers it.
Almost exactly an air at 20 °C
343 m/s is faster than 1 of the 10 references on this page.
Reference figures are measurements and are rounded; the unit conversion behind them is exact.
| Reference | Size | Yours ÷ theirs | Note |
|---|---|---|---|
| air at 0 °C | 331 m/s | 1.04× | |
| air at 20 °C | 343 m/s | 1× | |
| cork | 500 m/s | 0.686× | |
| lead | 1,210 m/s | 0.283× | |
| fresh water | 1,481 m/s | 0.232× | |
| sea water | 1,531 m/s | 0.224× | |
| wood along the grain | 3,300 m/s | 0.104× | |
| glass | 4,540 m/s | 1/13.2 | |
| steel | 5,100 m/s | 1/14.9 | |
| diamond | 12,000 m/s | 1/35 |
Worth knowing
- Sound travels 15 times faster in steel than in air, which is why you can hear a train through the rail before you hear it through the air.
- Diamond carries sound at 12 000 m/s — the fastest of any bulk material — because it is extraordinarily stiff for its density.
Frequently asked
Why does sound travel faster in solids?
Because sound is a pressure wave passed between neighbouring atoms, and the stiffer the bond, the faster the push travels. Density works the other way, which is why dense-but-soft lead is slow.
Does the speed of sound in air depend on pressure?
No — only on temperature, and on the gas itself. It rises by about 0.6 m/s for every degree Celsius.