Comment 55 for bug 274424

@anakin: I also have a dv3. Ubuntu 9.10 . The sound didn't work well. My Output of hardware is the same of you.
I did some trick but i hadn't worked. I also install a lot of thing pavu ...

I kept my Laptop up-to-date then
Finally I do the same as you.

sudo nano /etc/modprobe.d/alsa-base.conf

# then I added the following lines at the end of the file and REBOOTED!
options snd-hda-intel model=hp-dv5
options snd-hda-intel enable_msi=1

And then reboot. Miraculously, the sound work perfectly not only via headphone but also via Laptop's speaker.
I'll try this trick in a fresh intall ubuntu 9.10 as soon as possible