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 could imagine Susan's voice speaking to him.
( He ( ( could ( ( imagine ( ( Susan 's ) ( voice speaking ) ) ) ( to him ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (MD could) (VP (VB imagine) (NP (NP (NNP Susan) (POS 's)) (NN voice) (NN speaking)) (PP (TO to) (NP (PRP him))))) (. .)))