Some question about the VOICE.DAT in D.C.P.C

[EarthInKey]

Well,I extract it using crass but then the pcm file I got,well,can't be either to play or to transform into other format……
well,that's some kind of wave data files right?
I used some program to "transform" it into .wav but I get noise only

I use the same program to transform the "MUSIC" floder(store bgms),and all those pcms transformed and could be played by any music player.......

I look throgh the net and I found "ADPCM".......
Can anyone tell me how could I translate those .pcm into palyable files?