( ( ( The intensity ) ( of ( a ( sound wave ) ) ) ) ( ( ( is often ) ( measured ( in ( decibels ( ( ( ( The ( reference pressure ) ) is ) and ) ( ( P e ) ( is ( the ( root ( mean ( ( square ( pressure amplitude ) ) ( of ( the ( peak ( excess ( pressure -RRB- ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN intensity)) (PP (IN of) (NP (DT a) (JJ sound) (NN wave)))) (VP (VBZ is) (ADVP (RB often)) (VP (VBN measured) (PP (IN in) (NP (NP (NNS decibels)) (SBAR (S (S (NP (DT The) (NN reference) (NN pressure)) (VP (VBZ is))) (CC and) (S (NP (NNP P) (NNP e)) (VP (VBZ is) (NP (DT the) (NN root) (S (VP (VB mean) (NP (NP (JJ square) (NN pressure) (NN amplitude)) (PP (IN of) (NP (DT the) (JJ peak) (JJ excess) (NN pressure) (-RRB- -RRB-))))))))))))))) (. .)))
The intensity of a sound wave is often measured in decibels The reference pressure is and P e is the root mean square pressure amplitude of the peak excess pressure).
(ROOT (S (NP (NNP Decibel)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (VP (VBN used) (S (VP (TO to) (VP (VB measure) (NP (NP (DT the) (NN intensity)) (PP (IN of) (NP (JJ sound) (NNS waves)))))))))) (. .)))