( ( ( An examination ) ( ( in ( which sound ) ) ( waves ( are ( ( bounced off ) ( ( tissues and ) ( the echoes ) ) ) ) ) ) ) ( ( are ( converted ( into ( ( a picture ) ( -LRB- ( sonogram -RRB- ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT An) (NN examination)) (SBAR (WHPP (IN in) (WHNP (WDT which) (NN sound))) (S (NP (NNS waves)) (VP (VBP are) (VP (VBG bounced) (PRT (RP off)) (NP (NP (NNS tissues)) (CC and) (NP (DT the) (NNS echoes)))))))) (VP (VBP are) (VP (VBN converted) (PP (IN into) (NP (NP (DT a) (NN picture)) (PRN (-LRB- -LRB-) (NP (NNP sonogram)) (-RRB- -RRB-)))))) (. .)))
An examination in which sound waves are bounced off tissues and the echoes are converted into a picture (sonogram).
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-)) (VP (VBP echo) (SBAR (S (VP (VBZ is) (VP (VBN heard) (SBAR (WHADVP (WRB when)) (S (NP (JJ sound) (NNS waves)) (VP (VBP bounce) (ADVP (RB back)) (PP (IN from) (NP (DT a) (NN surface))) (SBAR (IN that) (S (NP (PRP they)) (VP (MD ca) (RB n't) (VP (VB pass) (PRT (RP through)))))))))))))) (. .)))