Well, it's a video or audio DVD?
Best solution would be to use Smartripper. Although it's outdated, I think it's the only one supporting correct LPCM decoding. All other rippers create a wav-file with lpcm-codec, which have to be decoded to normal PCM-wav using for example intervideo-audio-decoder in graphedit.
But I don't know, perhaps DVD-Decrypter works with LPCM as well.
Oh, or is the sound just ac3 or mpeg2, in that case you can use BeSplit , look at hxxp://dspguru.doom9.net
Hope this helps
Raist