The speed of a sound wave refers to how fast the disturbance or wave is passed from particle to particle. Since the speed of a wave is defined as the distance which a point on a wave travels per unit of time, it is often expressed in units of meters/seconds (m/s). The speed of any wave depends upon the properties of the medium through which the wave is traveling. The density of the medium will affect the speed the wave will travel at. A sound wave will travel faster in a less dense material rather than in a more dense material. The equation for the speed of sound is speed = distance/time. The following is an example of the equation.15
S = 330 meter/seconds
S = (330 X 60 X 60 X 3.3)/5280
S= 330M/s X 3.3ft./M X 3600sec/hr X 1 mile/5280ft.
Sound travels at 330 meters per second or 740 miles per hour.16 It is very interesting that sound travels much slower than light. Light travels at 186,000 miles per second; this is how we can see something happen on Earth at practically the instant that it happens in the sky. Sound on the other hand, takes some time to reach us. This explains why when you watch a fast airplane soar through the sky, the sound seems to be coming from a point in the sky that is far behind where you see the airplane.17 Only the Concorde and military aircraft travel faster than sound.
The speed of sound can also allow us to figure out how far away a distant lightning flash occurs by measuring the time for its sound, thunder, to reach you. Sound travels a mile in about 5 seconds. For the distances over which you can hear thunder, the light travels almost instantaneously. For example, if you hear thunder 20 seconds after you see a flash of lightning, then the lightning occurred 4 miles away.18
