Quote:
Originally Posted by

**PanamaHat** I'm not real saavy on the topic, but a quick google search yields decent results.

The formula to find the speed of sound in air is as follows:

v = 331m/s + 0.6m/s/C * T

v is the speed of sound and T is the temperature of the air. One thing to keep in mind is that this formula finds the average speed of sound for any given temperature. The speed of sound is also affected by other factors such as humidity and air pressure.

Notice the direct relationship between temperature and velocity.

Let's call it a draw on this one. I was drawing the analogy that because colder air is denser, then sound will travel faster. It's a lot more complicated than that because of the compressibility effects. Sound does travel faster in denser material and air does get denser with colder temperatures. However, sound in air travels by way of a compression wave and is not necessarily proportional to density when pressure (or compressibility) effects are in play.

This gives examples of the speed of sound in denser materials:

http://www.engineeringtoolbox.com/sound-speed-solids-d_713.html

Knowing that the speed of sound at sea level in dry air is 1100 ft/s, one can see in that chart that in water, the speed of sound is more than 4 times as fast - 4700 ft/s and in iron, 16 times faster.

This online calculator also shows that air gets denser with colder temperatures:

http://www.denysschen.com/catalogue/density.aspx

The difference is that air is compressible, so the affect of the sound wave on the air molecules is somewhat dissipated by increasing regions of pressure as the wave is propagated. The reason the formula you cited works is 1) Air is assumed to be a perfect gas (it's not) and 2) increased altitude (example of temperature decreasing) results in decreased density *and* pressure, so the two effects cancel each other out.

My assumption was that sound travels faster in denser media (correct), but that's not true for a gas.