On Ubuntu Linux Jaunty 9.04, Ubuntu Linux Hardy 8.04 and Ubuntu Linux Intrepid 8.10 the audio subsystem is mostly supported (multichannel autoconfiguration support is due in Ubuntu 9.10)

Very recent models may however have a few issues with microphone and multichannel audio. They can try out latest pulseaudio 0.9.15 (for autoconfiguration issues) and latest alsa 1.0.19 (for multichannel and microphone support).

If, for any reason, you have decided to try bleeding edge development drivers you can use the Bob Nelson script which I have further tweaked in order to prompt you with a choice among few most common modes to try out. Download it from here. Alternative script in case you get downloading timeout errors download from here.

Beware that these drivers, despite being stable, do not have any Ubuntu specific patch.

This script supports the following chipsets:

Intel HD Audio ICH6, ICH6M, ESB2, ICH7, ICH8, ICH9, ICH10, PCH, SCH
ATI SB450, SB600, R600, RS600, RS690, RS780, RV610, RV620, RV630, RV635, RV670, RV770
VIA VT8251/VT8237A,
SIS966, ULI M5461

After downloading the script you will need to do the following to the script:

- Change the permission of the script to make it executable.  To make the script executable type the following in a terminal:

chmod 755 alsa_setup

This command assumes you downloaded the script in your home folder

What this script does is:
- Download the ALSA modules
- Compile the modules
- Enable you to test different module options to see which one best suits you [new]
- Enable you to test the driver with different configurations [new]
- Change your  /etc/modprobe.d/alsa-base file
- Remove the installer files

To run the script type in terminal window

sudo ./alsa_setup

to see what is your audio CODEC go to System->Preferences->Sound and simply click on any drop down menu to read the code next to HDA Intel (i.e. ALC800)

now confront what mode better suits your specific CODEC by having a look at file

alsa-driver-1.0.19/alsa-kernel/Documentation/HD-Audio-Models.txt

If you need to add a mode not listed in the provided script type in terminal (where auto should be replaced with the correct codec mode)

sudo echo "options snd-hda-intel model=auto" >> /etc/modprobe.d/alsa-base.conf

Users of recent models (eg. dv4-1117) also benefited from enabling Message Signaled Interrupt (MSI)

sudo echo "options snd-hda-intel enable_msi=1" >> /etc/modprobe.d/alsa-base.conf

Ubuntu Wiki has a well done wiki concerning this issue: https://help.ubuntu.com/community/HdaIntelSoundHowto