The speed of sound is the distance traveled per unit time by a sound wave propagating through an elastic medium. To get the speed of sound, temperature is important than pressure because in an ideal gas, speed of sound changes with temperature. Use this online Speed of Sound Calculator to calculate sound speed at temperature 'T' based on air temperature which is expressed in degree and temperature designation given in Fahrenheit, Celsius, Kelvin, Rankine.
The speed of the sound varies with altitude only because of the changing temperature. You can calculate speed of sound in Miles/Hour, Knots/Hour, Metres/Sec, Feet/Sec and Km/Hour.