( ( ( ( ( Sound ( ( ( ( is , ) ( by definition ) ) , ) ( ( the vibration ) ( of matter ) ) ) ) , ) so ) ( it ( ( ( requires ( ( a ( physical medium ) ) ( for transmission ) ) ) , ) ( as ( do ( ( other kinds ) ( of ( ( ( mechanical waves ) and ) ( heat energy ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP Sound)) (VP (VBZ is) (, ,) (PP (IN by) (NP (NN definition))) (, ,) (NP (NP (DT the) (NN vibration)) (PP (IN of) (NP (NN matter)))))) (, ,) (IN so) (S (NP (PRP it)) (VP (VBZ requires) (NP (NP (DT a) (JJ physical) (NN medium)) (PP (IN for) (NP (NN transmission)))) (, ,) (SBAR (IN as) (S (VP (VBP do) (NP (NP (JJ other) (NNS kinds)) (PP (IN of) (NP (NP (JJ mechanical) (NNS waves)) (CC and) (NP (NN heat) (NN energy)))))))))) (. .)))
Sound is, by definition, the vibration of matter, so it requires a physical medium for transmission, as do other kinds of mechanical waves and heat energy.
(ROOT (S (NP (NNP Medium)) (VP (VBZ is) (NP (NP (DT the) (NN matter)) (SBAR (WHPP (IN through) (WHNP (WDT which) (NN sound))) (S (NP (NNS waves)) (VP (VBP travel)))))) (. .)))