That sound was pretty bad at this end . Did the video look ok?
Edit: It is an outside chance but we could try to force the correct decoder, I suspect this will not work:
Interestingly a modern FFmpeg has no such trouble with this audio codec. For those who are interested here is a sample:
avconv -c:a pcm_dvd -i /home/dad/Desktop/test/test.m2p \
-c:v libx264 -preset slow -crf 22 \
-c:a libmp3lame -q:a 4 \
which converts cleanly utilising the correct decoder...