perpendicular perpendicularbeing at right angles Related Articles: Glossary: angle of incidenceGlossary: normal lineTutorial: What is Sound?ReflectionMultibeam EchosounderMultibeam EchosounderProjector ArrayTutorial: ReflectionHow does sound propagate from air into water?How does sound propagate through sediment? Derek Sutcliffe2017-02-26T20:10:00-05:00