If you're traveling in space without any atmosphere, there is no sound barrier to break. The concept of the sound barrier only applies to objects moving through a medium, such as air or water, where the speed of sound is finite.
In a vacuum, like outer space, there is no medium for sound to propagate, so there is no sound barrier to be concerned about. Therefore, you wouldn't experience any particular effect by exceeding the speed of sound, as there is no sound to produce a sonic boom or cause any other audible phenomena.
However, it's worth noting that in space travel, there are other important barriers and considerations, such as the speed of light and the challenges associated with reaching and surpassing it. The theory of relativity becomes significant when approaching the speed of light, affecting time dilation, mass increase, and other relativistic effects. These factors would become more relevant as you approach velocities close to the speed of light, but they are distinct from the concept of breaking the sound barrier.