You probably remember from your science classes in school that the speed of sound is a constant. However, that constant speed is not necessarily the speed at which the sound reaches you. The material which sound is transferred through must be taken into consideration.
For example, how does density affect the speed of sound? Since sound waves involve the transfer of kinetic energy between adjacent molecules, the closer those molecules are to each other, the faster the sound travels. Therefore, sound travels much faster through solids than through liquids or gas. When understanding the speed of sound through different mediums or materials, there are several factors to consider besides density.
1. Elastic Properties
Elastic properties are the properties of a material that allow it to maintain its shape when you apply force to it. Materials with higher elastic properties return to their normal shape faster, making it easier for sound to travel through them. That’s why sound travels much faster through lead, for example, than rubber, which has very low elastic properties.
2. Air Density
Just as solid objects allow sound to travel faster than less dense ones, the density of gasses affect how quickly sound travels, as well. For example, sound will travel faster in hydrogen than regular air because it is a much denser gas. You’d expect sound to travel faster in colder air than hotter air, because colder air is denser. However, this isn’t the case, for the reason stated below.
Why does sound travel faster at higher temperatures than colder ones? When air is colder, the molecules are closer together, so sound transmission should be easier. This is true of solids and liquids, but gases behave a little differently. When gases heat up, their molecules move much more quickly. This increased vibration transmits the sound more quickly than it would in colder, but more static, air.
A List of The Speed of Sound Through Different Materials
In case you’re curious just how quickly sound travels through different mediums, here are a few of the different materials and how fast sound moves through them:
- Rubber — 60 m/s
- Air at 32 degrees — 331 m/s
- Air at 68 degrees — 343 m/s
- Air at 104 degrees — 355 m/s
- Lead — 1210 m/s
- Gold — 3240 m/s
- Glass — 4540 m/s
- Copper — 4600 m/s
Understanding the way sound travels through different mediums is an important part of how we at Soundproof Cow develop our sound blocking and sound absorbing materials. To learn more about how Soundproof Cow products can block unwanted sound and absorb harsh noises, visit SoundproofCow.com.