The speed of sound varies depending on altitude, temperature and the medium through which it travels. For example, at sea level in a standard atmosphere, at a temperature of 59-degrees Fahrenheit (15 Celsius), sound travels 761 miles per hour (1,225 km/p/h). At a temperature of 32-degrees Fahrenheit (0 Celsius) the speed of sound drops to 742 mph (1,194 km/p/h). In altitudes above sea level the speed of sound is again different and will vary depending on prevailing factors.