The propagation speed or velocity of sound depends on its nature, as well as its temperature and pressure.
In vacuum, sound does not travel because there is no matter to carry the waves. Sound insulation uses this property.
Propagation speed depends on the nature of the medium
| Materials (20°C) | Speed in m/s |
|---|---|
| Air | 344 |
| Water | 1 460 |
| Glass | 5 300 |
| Steel | 5 400 |
| Hard PVC | 2 400 |
| Concrete | 3 100 |
| Granite | 6 200 |
| Vacuum | 0 |
We know that some marine animals (dolphins, whales, etc.) communicate underwater using sounds. The whale song for example, is between 15 and 20 Hz. Research has shown that the whale song travels more than 3000 Km.
Propagation speed depends on the ambient temperature
The warmer it is, the better the propagation.
| Temperature in °C | Speed in m/s |
|---|---|
| - 10 | 325,4 |
| - 5 | 328,5 |
| 0 | 331,5 |
| + 5 | 334,5 |
| + 10 | 337,5 |
| + 15 | 340,5 |
| + 20 | 343,4 |
| + 25 | 346,3 |
| + 30 | 349,2 |
Propagation speed depends on the pressure of the medium
Sound travels less effectively horizontally than at higher angles, due to the change in density. This property has been taken into account in the design of outdoor theaters since antiquity.