Creating Bass,rumbling, etc.. Sounds for movie
 

How can I go about just creating bass in audition or fruity loops or any other app? I want it to be very specific not just random audio I've found online.

if you need something specific, you have to be more.... specific.
bass sound can be easily created by slowing down regular sound (like slammed door, or engine start, or bird song).
if you need musical bass, any sound handling program will do the trick.

Is it a mechanical rumble or an organic one you're looking for?

Either/or... Also if any of you have seen the movie "Iron Man" then when he's coming out of the cave and you hear the bass as he is stepping in the darkness, it's very VERY low bass which I love.

I'm interested in this as well.

"Environmental" effects that are not really musical.
That most of the times helps in creating the mood of a scene.

I guess the OP was referring to this, right?

The way to do this is to capture some sort of sound (refrigerator running, ceiling fan pushing air, cat purring, fingernails on chalkboard, whatever...) and lower the pitch alot. To keep it from falling apart, you'll want to capture the sound as 24 or 32 bit (better) with a 96 Khz sample rate. then slow the sound down (like creating slowmo in an NLE) using soundtrack pro, audacity, whatever audio editor you have access to that will deal with that level of sound.

This will stretch out the oscillations (frequency) of the wave making it a lower sound. Human hearing starts around 40 hz, so about there to 100hz will get pretty cool results. You can look at a spectrum analyzer plugin (or a dancing lights EQ plugin) to see where it's settled when you slow it down.

Before you knock yourself out chasing that kind of movie theater quality EFX sound, you might want to start by setting aside some reasonably serious money for good monitoring in your editing suite, or don't expect to HEAR accurately what you're trying to mix.

Yeah, it starts with good sound design, but thats a guessing game unless you can EQ and mix your tracks with an ear for what an actual 5.1 theatre environment will do to your mix.

True story - I once helped a guy with his low budget digital film, and delivered him what I knew to be really good sounding dialog tracks. He took those and "mixed" them on his home editing system, but for the big premier, when his "sounds good on my home system" mix hit a larger college theater, we all painfully discovered that ALL the dialog in the movie was summed to mono OUT OF PHASE and was almost impossible to listen to.

A good example of mixing on one system, then moving those recordings to a whole different level of sound system. Sometimes you get some really nasty surprises.

For what it's worth.

If you're looking for purchasing stuff, the "Hollywood Edge" series of sfx are really good.

If you use Audacity, it's got a very nice tone generator that allows you to specify the exact frequency you want. You could generate a very low tone then run it through some reverb plugins or a phaser or something to get some different variations on it.