Subject	longitudinal wave
Predicate	be referred as
Object	pressure waves
Modality	Modality Occurrences sometimes 2
Polarity	POSITIVE
Plausibility	0.4780
Neighborhood Sigma	0.4874
Local Sigma	1.0000
Example Sentences	Sentence Occurrences Source longitudinal waves are sometimes referred to as pressure waves 2 Answers.com Questions