A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound. It can be viewed as a Doppler effect on steroids; sonic booms generate an enormous amount of energy and sound like explosions.

The first man-made object to ever create this phenomenon was a bullwhip. The ‘crack’ of the whip is a result of this sonic boom. This version of a Doppler effect is demonstrated by.

When the sound source passes through the air, it creates a series of pressure waves. These waves are traveling at the speed of sound, and as the speed of the sound source increases, the waves, not being able to get out of each other’s way, are forced together.

They eventually merge into a single shock wave traveling at the speed of sound. This is a critical speed, known as Mach. The shock waves radiate out from the sound source, and create a “Mach cone’. The half-angle, α, can be found using the equation.

\( \sin a=\frac{v_{s}}{v_{r}} \)

From previous atoms, we know that v_s / v_r is the sound source’s Mach number.

At the front of the sound source, there is a sudden rise in pressure, while at the end of the source, there is a decreasing pressure. This ‘overpressure profile’ is known as an N-wave. There is a big boom when there is a sudden change in pressure, and since the pressure changes twice, this is a double boom.