The speed of sound, known as Mach 1, varies depending on the medium through which a sound wave propagates. In dry, sea level air that is around 25 degrees Celsius, Mach 1 is equal to 340.29 meters per second, or 1,122.96 feet per second.
Mach 1 rises with the density of the medium. In 25-degree Celsius fresh water, sound propagates at 4,940.1 feet per second. In sea water Mach 1 is equal to 5,148 feet per second, or nearly 3,600 miles per hour. In air the speed of sound is a function of temperature only. Though supersonic aircraft measure speed as a function of external air pressure, this is only an approximate method caused by technical limitations.