Baffles

[danielf]

Can someone please define for the what an infinite baffle is/how a baffle works/what its supposed to do?  :uglystupid2:
Textbook sucks...

[ReVeL]

Never heard of it. :/

What area of study is it?

(I do photonics not Sound as the detailed study - hopefully thats the reason I don't know).

[danielf]

Yeah sound

[BiG DaN]

baffles prevent the different frequencies and out of phase sound from
destructively interfering with eachother thus producing high fidelity sound

[cara.mel]

It stops the sound produced from the back of the speaker interfering with the sound produced from the front of it

Infinite baffle = long infinite line the sound can't pass around. can also be a box

[danielf]

gotcha thanks

[Mao]

A quote from the VCAA 2006 Physics Exam about the role of speaker boxes:
"A common misconception was that the rearward sound wave was reflected from the back of the box, became in phase and constructively interfered with the front wave."
I always thought that this was true (and I just did a TSFX 06 exam and this was a correct answer)
The answer is just that is prevents the sound at the rear of the cone from diffracting around the diaphragm and cancelling the front wave.
Can anyone improve on this/explain to me why the first thing is a 'misconception'?

it is possible. this is the case with the "ports" in sub-woofers typically found in cars, that use reflection of sound from the rear to constructively interfere with the output.

but normally [assuming this was the question], infinite baffles [enclosed boxes] are used so that out-of-phase sounds at the back cannot diffract around the baffle and destructively interfere with the output.