ROM Hack Hacking help: Voice hacking

[Kysafen]

Personally, I'd love to make a voice hack of Tales of The World: Narikiri Dungeon 1 and 2, along with Tales of Phantasia. It's not a project, it's not even a priority; it's just something I'd like to try for fun. Keep in mind the most extensively I ever hacked music was replacing music tracks in the same game, so it's pretty easy to see I'm a newbie hacker.

So, how would I go about replacing voices? Yes, I'm aware it's not a matter of "OH! I'LL JUST PUT AN MP3 INTO TEH GAYM!" What I want to know is:

1. Could I replace voice data using Sappy?
2a. If yes, how could I replace the voice data using it?
2b. If no, what would I need TO replace voice data?

 

[FAST6191]

1. Probably not, I would keep the tool handy though.
2. GBA games do not have a common sound file format like the DS, there are some that are shared (see golden sun stuff by Atrius and perhaps pull apart http://www.romhacking.net/hacks/563/ ) but by and large it is not all the same. You also have problems if a game decided to go with midi rather than "wave" sampling (not a terribly hard ASM hack if you do not care about space but definitely into the ASM world).
First you have to find the sound format, VBA-SDL-h being the tool of choice ( http://www.romhacking.net has it and a good guide to the basics- finding the title screen) or I suppose you could try corruption.
GBA sound is a weird and wonderful thing so http://nocash.emubase.de/gbatek.htm#gbasoundcontroller and http://belogic.com/gba/ are required reading.

Finally for tales of phantasia grab the European version as they actually sorted that one out nicely aside from the font which is sorted with this:
http://www.romhacking.net/hacks/130/

If this is more about intellectual curiosity you now also have two different versions to play against each other and figure out differences.