The speed of sound varies depending on the type of medium through which it moves, explains Livescience. When traveling through Earth's atmosphere at sea level, and with a constant air temperature of 59 degrees Fahrenheit, sound travels at just over 761 miles per hour.
Sound is a disturbance that travels through the medium of the atmosphere. The atmosphere is made of a mix of gases whose molecules move more slowly at colder temperatures, reducing the speed of the sound waves that travel through them. The speed of sound is also reduced in environments with lower atmospheric pressure, explains a NASA website.