When sound waves enter a vacuum, they cannot propagate or travel through it. A vacuum is a space devoid of matter, including air or any other medium necessary for sound wave transmission. Sound waves require a medium to propagate because they rely on the physical interaction between particles to transmit energy.
In a vacuum, there are no particles for the sound waves to compress and rarefy, and therefore, they cannot propagate or continue their transmission. Instead, the sound waves simply cease to exist or dissipate. Without a medium to carry and transmit the energy of the sound waves, they cannot travel or be detected in a vacuum.
It is worth noting that space is mostly a vacuum, as it is devoid of air or other matter. Therefore, sound cannot travel through the vast majority of space. However, there are instances where sound can still be transmitted in space, such as within spacesuits or within spacecraft where there is a medium, like air, that allows for sound wave propagation.