Sound generated by airflow has been around and reasearched for a long time. The increased use of fluid machines and engines has led to an increasing level of noise generation, and hence to an increasing interest in this area of research.
A sonic boom is a loud noise caused by an aircraft travelling faster than the speed of sound which is mach one.. The sound propagates along the figure which is called the mach cone. The boom is due to a combination of volume and lift. While the boom due to volume can be virtually eliminated (Busemann, 1935), the boom due to lift can only be minimized.
The minimum sonic boom generally does not correspond to the best aircraft. There is among others: sonic boom minimization at given drag; minimization at given volume, etc. (Seebass, 1998). Because the shock energy is nearly conserved as the shock radiates, its strength decays only slightly with the distance from the aircraft. Minimization is not straightforward, because it is constrained by structural, aerodynamic and design parameters, and not least by the variation of the thermo-dynamic properties of the atmosphere.
Click on the following link to hear a demonstration of a sonic boom!!!!
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Fig 1 and Fig 2: are both representations of sound waves when a aircraft or other objects are moving faster than the speed of sound.
The figure above shows several different common aircraft and the near speed of which they fly.
