The speed of sound is often confused with the frequency of a sound. It is helpful to remember that the frequency refers to how often while the speed refers to how fast. When discussing the speed of sound it is important to understand that the speed of a sound wave refers to the distance that a point on a wave travels per unit of time. The speed of sound is often stated in units of meters/second. A mathematical equation for this is:
Speed = distance/time
The faster a sound wave travels, the more distance it will cover in the same period of time. The speed of sound depends on the type of properties the wave is traveling through. Two main properties contribute to the speed of a sound wave. Inertial properties refer to the density of the medium that the sound wave is passing through. The greater the inertial properties or the heavier the medium, the slower the wave will pass through. A sound wave will pass quicker through a less dense medium. For example, sound travels quicker through helium then through air, since helium is less dense then air. Elastic properties also affect the speed of sound. These properties refer to how materials maintain their shape under force. Air pressure is an elastic property that affects the speed of sound. The pressure of air will affect the density of the medium, while the temperature of the air affects the strength of the particles passing through the medium. Basically, the speed of sound depends on what the sound wave is passing through. Sound travels faster through solids than liquids and faster through liquids than gases. Sound cannot travel where there is no air, which is why in space it is silent. The speed of sound is about a million times slower than the speed of light. Light travels through air at approximately 300,000,000 meters per second. (Glenbrook/Physics Classroom, 6/10/03)