Answer:
Sound barrier :
The sound barrier is defined as a "barrier" that travels in all directions (because we are talking about sound waves) at the typical speed of sound in the air (1235.5 km/h). It should be noted that the name of "barrier" was given because it was previously considered a physical limit that prevented large aircrafts from traveling at supersonic speed (a situation that was evident in fighter planes during World War II, having problems with compressibility when flying at high speeds). However, today many planes are capable of overcoming that barrier without problems.
When the Sound barrier is broken :
When an airplane approaches the speed of sound (defined in the upper lines), it can be observed how the shape of the air that flows around it changes, because the wave fronts are grouping more and more.
Then, when the plane exceeds the speed of sound (the sound barrier), something known as sonic boom or sonic explosion occurs, which is nothing more than what our ears can hear when the shock wave caused by the plane exceeds the speed of sound.
It should be noted that this explosion can be annoying to the human ear.
