THEY ARE READY, returned Susan's voice in the back of his mind.
( THEY ( ( ARE ( ( READY , ) ( ( returned ( ( Susan 's ) voice ) ) ( in ( ( the back ) ( of ( his mind ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP THEY)) (VP (VBP ARE) (NP (NP (NNP READY)) (, ,) (VP (VBN returned) (NP (NP (NNP Susan) (POS 's)) (NN voice)) (PP (IN in) (NP (NP (DT the) (NN back)) (PP (IN of) (NP (PRP$ his) (NN mind)))))))) (. .)))
He couldn't remember what Susan's voice sounded like.
( He ( ( ( could n't ) ( remember ( what ( ( ( Susan 's ) voice ) ( sounded like ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (MD could) (RB n't) (VP (VB remember) (SBAR (WHNP (WP what)) (S (NP (NP (NNP Susan) (POS 's)) (NN voice)) (VP (VBD sounded) (PP (IN like))))))) (. .)))