EMI Viewer 2.6
I've dug out my PS2 copy of EMI and its a German PAL version. I can upload some files if you need to compare.
I tried changing 0x8002 to other values at that offset - none seemed to make any difference - the screen isn't blacked out. Are you sure that's the only value you changed?
[Edit] I've had a quick look at the PS2 voice files, I havent done anything more than just look at them in a hex editor but my guess is that they use the PS2 VAG format, which is an adpcm variant.