What phenomenon occurs when an object travels faster than the speed of sound, producing a loud sound?

When an object travels faster than the speed of sound, it creates a phenomenon known as a sonic boom. This occurs because the object compresses sound waves in front of it as it moves at supersonic speeds. As these waves pile up, they generate a shock wave, which ultimately leads to a loud noise, commonly referred to as a sonic boom.

In contrast, the other terms refer to different concepts. The noise barrier typically relates to the phenomenon of sound not being able to penetrate certain materials efficiently, rather than a speed-related occurrence. Sound waves are the vibrations that travel through a medium, but they do not inherently cause the loud sound associated with breaking the sound barrier. An echo refers to the reflection of sound waves off surfaces, creating a delayed repetition of the original sound. Thus, the sonic boom is specifically tied to supersonic speed and the resulting shock wave, making it the correct answer in this context.