in sound what is meant by contractions and rarefactions

Question

rina.r · Answer

http://physics.tutorvista.com/waves/longitudinal-waves.html this might help!

anonymous · Answer

Its compressions and rarefractions!..

have u seen ur speaker woofers ? what do they do.. they move in and out?.. when they move out.. they push the air immediately close to its surface.. this compresses the air right?

imagine people standing one arm distance from each other having a spring attached..

and i (woofer) push a person.. then i compress .. then they expand.. do u get the idea? :P

anonymous · Answer

Does that make sense? :P

chenping · Answer

haha, yea, just air particles colliding. and then SHM comes! :)