( Ultrasound ( ( ( ( ( is sound ) ( at ( frequencies ( above ( 20 kHz ) ) ) ) ) , ) ( too ( high ( to ( be ( detected ( by ( normal ( human hearing ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Ultrasound)) (VP (VBZ is) (ADJP (JJ sound)) (PP (IN at) (NP (NP (NNS frequencies)) (PP (IN above) (NP (CD 20) (NN kHz))))) (, ,) (ADJP (RB too) (JJ high) (S (VP (TO to) (VP (VB be) (VP (VBN detected) (PP (IN by) (NP (JJ normal) (JJ human) (NN hearing))))))))) (. .)))
Ultrasound is sound at frequencies above 20 kHz, too high to be detected by normal human hearing.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (NN sound)) (SBAR (WHNP (WDT that)) (S (VP (VBZ has) (S (NP (DT a) (NN wave) (NN frequency)) (ADJP (JJR higher) (SBAR (IN than) (S (NP (DT the) (JJ human) (NN ear)) (VP (MD can) (VP (VB detect) (NP (NN ultrasound))))))))))))) (. .)))