DVD Sound Quality Poor

I got a DVD of Idaho Transfer from Netflix. The sound was so low I had to turn up the volume all the way and it still wasn't loud enough for my mom who has bad hearing. I could hear it but it was a bit lower than I would prefer. In other posts people mention getting it in a set of Science Fiction or futuristic movies. The sound is ok on that version apparently. Someone suggested getting it on VHS rather that DVD and maybe that was because of the sound.

I just saw this movie for the first time since 1973. The ending is the only thing that both my mom and I remembered. I liked the movie but you have to listen to the dialog carefully, and the sound was poor. I gave it a 7.