I have thought of a solution. Try to get a program called DVD Decrypter (it has being banned, I think, so it might take a while to find on the web), use this to remove the css (copy Wright code thingy) from the DVD while ripping it to the hard drive. This should take no more than about 15 minutes max. Now that the css has being removed you should be able to open it in many programs such as NERO where you can edit freely. If Nero is no good try opening the decrypted movie file in a video editing program such as ULEAD VIDEO STUDIO or ADOBE PREMIAIR then get rid of all the footage that does not contain the audio you want, then save as a sound file...DONE
Hope this jumble of words provides some help