Sonic boom

When an aircraft flies at supersonic speeds, shock waves are generated from various parts of the aircraft. These shock waves integrate as they propagate over long distances in the atmosphere, creating an N-shaped pressure waveform that causes two abrupt pressure fluctuations on the ground. This phenomenon is known as a sonic boom, characterized by an impulsive, loud sound.

The Concorde was allowed to fly at supersonic speeds only over the sea, and not over the land, due to its loud sonic boom. Mitigation of sonic booms has become a major technical challenge for the realization of the next-generation supersonic civil transport.

Currently, the International Civil Aviation Organization (ICAO) is discussing the formulation of international standards for sonic booms. JAXA contributes to the development of these standards by providing the results of the D-SEND project and the results of evaluations testing human perception of sonic booms by using a sonic boom simulator.

Sonic boom simulator

The sonic boom simulator is a small booth that reproduces the same sound pressure changes as the actual sonic boom by using large low-frequency loudspeakers mounted on the walls.

JAXA’s sonic boom simulator uses eight large low-frequency loudspeakers (four each on the front and the back) and four small high-frequency loudspeakers to play back the simulated sonic boom sound. This simulator is used to assess the acceptability of the sonic boom by asking subjects to evaluate sonic boom sounds with various waveforms.

July 11, 2024