( ( Acoustic waves ) ( ( travel ( with ( ( ( the speed ) ( of sound ) ) ( which ( depends ( on ( ( the medium ) ( they ( 're ( passing through ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Acoustic) (NNS waves)) (VP (VBP travel) (PP (IN with) (NP (NP (DT the) (NN speed)) (PP (IN of) (NP (NN sound))) (SBAR (WHNP (WDT which)) (S (VP (VBZ depends) (PP (IN on) (NP (NP (DT the) (NN medium)) (SBAR (S (NP (PRP they)) (VP (VBP 're) (VP (VBG passing) (PRT (RP through)))))))))))))) (. .)))
Acoustic waves travel with the speed of sound which depends on the medium they're passing through.
(ROOT (S (NP (NP (DT The) (NN speed)) (PP (IN of) (NP (NN sound)))) (VP (VBZ depends) (PP (IN on) (NP (NN medium)))) (. .)))
The speed of sound depends on medium.