I am looking for a definitive explanation on what sound file formats can be used for FO3.

Radio station - mp3 and wav
NPC dialogue - wav or ogg
Sound - wav only? ogg or mp3 possible? Through scripts?

well you can declare both wav and mp3 files as "Sounds" in the geck, ogg however wont work, yes ive tried using the games dialogue and it wont add them unfortunately, dont know of another way to do it.
Mp3 files however cause microstutter for some people and wavs are more commonly used to avoid it, if you open up the sounds.bsa you'll even notice bethesda have about 3 different versions of their radio songs, in mp3 stereo, mp3 mono, and wav mono. Mp3 mono is used by default for radio songs. Wav files for ambience and sound fx. Ogg for dialogue, but im a little unsure how that gets declared.

Hope that helps a bit

To use ogg for dialogues, you record a silent wav file in the GECK, then rename your ogg sound file with the name of the wav file that was generated (and put it in the same directory where the wav file was generated). You can set MP3's as sound in the GECK? Really? Can anyone else confirm this works in game?

I have tried but not ever been able to get mp3s to play. Though I've heard it can be done. I use wav because of the reasons mentioned. MP3s are encoded and require decoding before playing which is where the stutter comes from. wav format does not require decoding and is therefore easier on the game to play. The downside being that wav files are much bigger.

For dialog, take a look at this: http://www.tesnexus.com/downloads/file.php?id=7877

According to that, you need a wav file in order to hear anything while in the dialog editor and to generate the lip files. The game will then play mp3 files of the same name. He doesn't mention it in the video, but I'd assume once you're ready to release your mod (or just don't need to do things with dialog anymore), you'd want to delete the wav files to save space. Also, it seems that while with FO3 they added support for the game to use ogg format in place of mp3, it's not reflected in the GECK - that is, in the "Edit Response" form, the audio file paths always specify an mp3 extension. I'd assume you can still use mp3's for dialog too, but I've never tried to create new dialog myself, so you'd need someone else to confirm this - or just test it yourself.

For Sounds, razorwire is right that the Sound form won't accept ogg files, but wav or mp3 are fine. Also if you've never noticed, you can specify a folder here instead of a single file, and each time that defined Sound is used it will randomly play a valid file in that folder (sub-folders are ignored).

I don't think you can use MP3 for dialogue. I tried and couldn't get it to work. You can use ogg though, if following the steps I mentioned above. Lip sync generation is broken as of patch....version I can't remember. But it's broken from all the sources I've consulted. I had to scour extracted lip sync/dialogue sound files to find lip sync files that 'fit' my custom dialogue.



Are you serious? Can someone confirm this works?

[edit]
Bloody hell, where were you a day ago when I was trying to find a script that would allow me to randomize sounds? Well, at least I learn something stuff about scripting...

You can make lip file for Fallout 3, but it reqires using the http://www.elderscrolls.com/downloads/updates_utilities.htm and something called http://www.tesnexus.com/downloads/file.php?id=13742. And you do not need Oblivion to get this to work. The instructions are in the Lip_Tamplate readme.

Yes, I can - I've made new Sounds with multiple wavs that work that way. Plus, just take a look at the vanilla Sounds in the GECK. Many, if not most, of the weapon and fx sounds are set up this way. Open one up and keep hitting the "Play" button.

I figured that out by accident Now my Molerats sound like freak/monster wasteland pigs on fire.... don't ask... 0_o

I set FXFireSconceLP02 (FX\FX\Fire\Sconce) as the looping sound for my duplicate of the OasisTorch01. If there's just one, everything works fine. But if I add a few to roughly the same area - sometime all have sound, sometimes all have no sound, sometimes some have sound and some not. Seems really spotty for some reason. Anyone else have this issue when using a path to multiple sounds?

I can point it to any of the wavs in FX\FX\Fire\Sconce, and all of them always work - but it's always the same sound :\

I have also never been able to make MP3's work for voice acting dialogue, and I reference this in my Audio Holotape tutorial (which covers alot of the sound/recording aspects). I too use .WAVs as I have not tried working with .OGG files yet. I assume these work, but MP3s must have special conditions under which they work or some kind of flagging as they are not just plug-and-play from my experience...