Does sound ever stop traveling If so when?

In theory, sound never truly stops traveling. Sound waves can travel through various media, such as air, water, and solids, and they weaken and disperse over time and distance due to factors like absorption and scattering. However, there are a few instances where sound waves may effectively cease to exist or become unnoticeable to the human ear:

1. Vacuum: Sound waves require a medium to propagate. In a vacuum, where there is no matter or molecules present, sound cannot travel. Therefore, in the absence of a medium, sound waves cease to exist.

2. Distance and Absorption: As sound waves propagate through a medium, the energy carried by the waves dissipates due to absorption and dispersion. The farther the sound travels, the weaker it becomes. Over vast distances, the sound may become so faint that it is no longer detectable by the human ear. This effect is more prominent in denser media like water and solids compared to air.

3. Acoustic Barriers: Engineered acoustic barriers, such as soundproofing materials, can effectively block or absorb sound waves. These barriers are designed to reduce the transmission of sound, and when sound waves encounter such obstacles, they can be significantly dampened or completely stopped.

4. Frequency and Perception: The human ear can only perceive sound waves within a certain range of frequencies, typically between 20 Hz and 20,000 Hz. Sound waves that fall outside this range, either too low (infrasound) or too high (ultrasound), are not audible to humans. Therefore, for frequencies beyond our hearing range, sound waves effectively stop existing in terms of our perception.

In practical scenarios, sound waves eventually become too weak or are blocked to a point where they are no longer noticeable to humans or have any significant impact. However, from a theoretical standpoint, sound waves never truly stop traveling unless they encounter an absolute vacuum.