When an object moves faster than the speed of sound in a medium, it creates a shock wave known as a sonic boom. The sonic boom is a result of the sudden change in air pressure caused by the object moving faster than the speed at which sound waves can propagate.
After the sonic boom occurs, sound waves continue to propagate in the usual manner. However, there are a few important points to consider:
Shock wave propagation: The shock wave generated by an object breaking the sound barrier travels outward from the object. It consists of a complex pattern of compressed and rarefied air regions. The shock wave can cause a sudden, loud noise that is heard as a sonic boom.
Speed of sound: While the object itself may be traveling faster than the speed of sound, the sound waves it generates behind the shock wave still travel at the local speed of sound in the medium. In the case of air, this speed is approximately 343 meters per second (depending on various factors like temperature and humidity).
Directional propagation: Sound waves generated by an object moving faster than the speed of sound will propagate in all directions, similar to sound waves generated by any other source. However, the sound waves will be concentrated within the wake region behind the object, as it is here that the compressed air behind the shock wave acts as a medium for sound propagation.
Doppler effect: As an object approaches and then exceeds the speed of sound, the properties of sound waves emitted by the object can be affected by the Doppler effect. This effect causes the frequency of the sound waves to be compressed in front of the object and stretched behind it, resulting in a perceived change in pitch for an observer relative to the moving object.
It's important to note that the effects of breaking the sound barrier and sonic booms are primarily associated with supersonic aircraft, such as fighter jets. These phenomena are not commonly encountered in everyday situations.