I know that particles don't go from one end to the other, they just vibrate and transfer sound energy to next particle. How do they return to equilibrium again? Do they return just after collision with next particle in the medium or do they return as a consequence of reflecting off objects like a slinky? And if they return after reaching objects and reflecting back, is that how we hear our own sound. What will happen if you levitate in the atmosphere arbitrarily at one place (assumption), will you be able to hear your sound provided there are no objects around?


1 Answer 1


The mean free path of a molecule in air (STP) is around 100 nm, so the collision time is on the order of 0.3 ns...3 GHz. The sound wave is so much slower, it's effectively a background static pressure as far as "equilibrium" is concerned.

  • $\begingroup$ That's a very interesting approach I've never thought of before. Could you provide some sources that treat the concept from this perspective? $\endgroup$
    – ZaellixA
    Commented Jul 25, 2023 at 17:03
  • 1
    $\begingroup$ no sources, but this is how the one considers light interacting with an atom, in the 1st approximation. $\endgroup$
    – JEB
    Commented Jul 26, 2023 at 2:35
  • $\begingroup$ @JEB Thanks for answer. Got clarity. Can you also answer the other questions about reflection of sound and one assumption asked above? $\endgroup$
    Commented Jul 27, 2023 at 14:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.