Using Audio

I'm new to using Arduino and I was wondering if it's possible to store sounds on an SD card that can be played through Arduino. I have 5 flex sensors set up to an Uno, is it possible to play specific sounds when different parameters are reached? For example, if a sensor outputs a range from 0 to 5, then play the sound defined as "2" in the SD card? This is for a very important project and none of my teachers or family have any experience with this. Any help would be greatly appreciated.

You can make a piezo disk buzz to certain notes with an Arduino. But if you want to play like a real MP3 or something you need external hardware. There are shields that will do that sort of stuff. So it really depends on what sorts of "sounds" you are talking about.

I'm trying to output individual letters, what shields would you suggest?

jai-cab:
I'm trying to output individual letters, what shields would you suggest?

Individual letters? So spoken voice kind of thing? I would start here.