The speed of sound (), also known as the sound velocity or the sonic speed, represents the speed at which pressure waves (sound waves) travel through a medium, such as air. In the context of aircraft design and aerodynamics, the speed of sound is a critical parameter because it defines the boundary between subsonic and supersonic flight.
The formula for calculating the speed of sound () in dry air at a specific temperature is given by:
   
- is the speed of sound (typically in meters per second or feet per second).
- is the ratio of specific heats (dimensionless), approximately equal to 1.4 for dry air.
- is the specific gas constant for dry air (approximately 287.05 J/(kg·K) in the SI unit system).
- is the absolute temperature of the air (in kelvin).