# Do sound waves bend and/or diffract?

Sound waves are normally mechanical wave i want to know whether the sound wave bends if it bends does it undergo diffraction just like light wave?

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You say You have a "new" theory to unify sound and light waves. How does that fit to asking such low-level-questions on sound? –  Georg May 18 '11 at 17:14
Do sound waves diffract? Of course they do. Diffraction is nothing more than waves adding together linearly. Try it with pebbles in a pond. –  Mike Dunlavey Oct 12 '11 at 5:09
Mr.Georg thank you very much ,for unification of that sound and light i waht to know that whether sound waves bneds or not clearly that's why i posted this question –  pavan Jan 3 '12 at 17:27

Sure sound waves diffract. That's why two people can have a conversation, even if there's an object in between them.

When I teach this stuff, I often walk out of the classroom, to a place where the students can't see me, just to show that they can still hear me. That illustrates that sound waves diffract, and moreover that they diffract much more than light waves under these circumstances. That's because the wavelength of sound waves is comparable to the other length scales in the situation, whereas the wavelength of light waves is much shorter.

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The fact an obstacle in the way doesn't stop you from hearing someone talk doesn't prove the diffraction of sound waves. I can see around a corner with a mirror, who's to say we're not hearing an echo when you lecture from outside the room? –  Mark Eichenlaub May 18 '11 at 21:48
@Mark: because then you would hear a sizable echo before he left the room. –  Ron Maimon Sep 24 '11 at 8:00

Sound waves do, indeed, bend. In an underwater thermal gradient the sonar waves can bend enough to create blind spots, so that you can not "see" a target that would ordinarily be well within sonar range.

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Very good point. Are you perhaps referring to the SOFAR channel? –  voithos May 18 '11 at 17:55

The other example is the difference in how well sound carries up/down wind. Wind velocity increases with height (at least in the near surface boundary layer), this shear means that soundwaves traveling upwind are diffracted upwrds, but waves travelling downwind are diffracted downward, so that in the downwind direction the sound can travel in a channel near the ground.

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