Sound waves do propagate through a medium, but they do not travel indefinitely due to a phenomenon called sound attenuation. Several factors contribute to the dissipation of sound waves over distance:
Geometrical spreading: As sound waves propagate through space, they spread out in a spherical manner. The energy carried by the waves gets distributed over a larger and larger area as the distance from the source increases. Consequently, the sound intensity decreases, resulting in a decrease in the perceived loudness of the sound.
Absorption: Sound waves can be absorbed by the medium through which they travel. When sound encounters a material, such as air, water, or solids, some of its energy can be converted into other forms, such as heat. The absorption depends on the properties of the medium and the frequency of the sound. High-frequency sounds are generally absorbed more quickly than low-frequency sounds.
Scattering: When sound encounters small particles or irregularities in the medium, it can scatter in different directions. This scattering causes the sound energy to spread out and become less focused, leading to a decrease in sound intensity over distance.
Atmospheric conditions: Factors such as temperature, humidity, and wind can affect the propagation of sound. Temperature variations in the atmosphere can cause sound waves to refract or bend, altering their direction of travel and potentially leading to sound dissipation. Wind can also disrupt the propagation of sound by causing turbulence and scattering.
Interference and diffraction: As sound waves encounter obstacles or pass through openings, they can undergo interference and diffraction effects. These phenomena can cause the sound waves to interact and cancel each other out in certain regions, resulting in reduced sound intensity.
It's important to note that the extent to which sound dissipates depends on various factors, including the initial intensity of the sound, the characteristics of the medium, and the distance from the sound source. In practical terms, the dissipation of sound waves limits the distance over which sound can be heard clearly, and it eventually becomes indistinguishable from background noise.