No, sound waves do not persist in the universe indefinitely. Sound waves are mechanical waves that require a medium, such as air, water, or solids, to propagate. When we speak or make any sound, we create sound waves that travel through the surrounding medium.
However, sound waves gradually dissipate and lose energy as they propagate through the medium. This energy loss occurs due to various factors such as absorption, scattering, and conversion of sound energy into other forms, such as heat. Over time, the sound waves become weaker and eventually become too faint to be detected by our ears or instruments.
Furthermore, once sound waves reach the boundaries of the medium they are traveling through, they can reflect, refract, or diffract. These interactions can cause the sound waves to change direction or become distorted. Some of the sound energy may be reflected back towards the source, but a significant portion is typically absorbed or dissipated.
In summary, while sound waves propagate through a medium and can travel considerable distances, they eventually dissipate and fade away due to energy loss and interactions with the environment. Therefore, the sounds we utter do not remain as sound waves in the universe forever.