noun
compressional wave; longitudinal wave
Physics term for a wave in which particle displacement is parallel to the direction of propagation, creating alternating regions of compression and rarefaction. Used in acoustics, seismology, and solid mechanics.
音波は空気中を疎密波として伝わる。
Sound waves travel through air as compressional waves.
地震のP波は疎密波の一種である。
Seismic P-waves are a type of longitudinal wave.
横波 (transverse wave) is the counterpart where particle motion is perpendicular to wave direction.
Compound of 疎密 (そみつ, 'sparseness and density') + 波 (は, 'wave'), literally 'sparse-dense wave', referring to the alternating regions of compression and rarefaction.