How Fast Does Sound Travel Temperature Elevation?

How Fast Does Sound Travel Temperature Elevation? Altitude Temperature mph Sea level15 °C (59 °F)761 11,000 m−20,000 m (Cruising altitude of commercial jets, and first supersonic flight) −57 °C (−70 °F) 660 29,000 m (Flight of X-43A) −48 °C (−53 °F) 673 What is the speed of sound at altitude? Altitude Speed of Sound Feet