Editing Longitudinal wave (section)

== Pressure waves ==
The equations for sound in a fluid given above also apply to acoustic waves in an elastic solid. Although solids also support transverse waves (known as [[S-waves]] in [[seismology]]), longitudinal sound waves in the solid exist with a [[Speed of sound|velocity]] and [[Acoustic impedance|wave impedance]] dependent on the material's [[density]] and its [[Stiffness|rigidity]], the latter of which is described (as with sound in a gas) by the material's [[bulk modulus]].<ref>Weisstein, Eric W., "''[http://scienceworld.wolfram.com/physics/P-Wave.html P-Wave]''". Eric Weisstein's World of Science.</ref>

In May 2022, NASA reported the [[sonification]] (converting astronomical data associated with pressure waves into [[sound]]) of the black hole at the center of the [[Perseus Cluster|Perseus galaxy cluster]].<ref name="NASA-20220504">{{cite news |last1=Watzke |first1=Megan |last2=Porter |first2=Molly |last3=Mohon |first3=Lee |title=New NASA Black Hole Sonifications with a Remix |url=https://www.nasa.gov/mission_pages/chandra/news/new-nasa-black-hole-sonifications-with-a-remix.html |date=4 May 2022 |work=[[NASA]] |accessdate=11 May 2022 }}</ref><ref name="NYT-20220507">{{cite news |last=Overbye |first=Dennis |authorlink=Dennis Overbye |title=Hear the Weird Sounds of a Black Hole Singing – As part of an effort to "sonify" the cosmos, researchers have converted the pressure waves from a black hole into an audible … something.|url=https://www.nytimes.com/2022/05/07/science/space/astronomy-black-hole-sound.html  |date=7 May 2022 |work=[[The New York Times]] |accessdate=11 May 2022 }}</ref>