If you have an acer aspire one series netbook you don't have to do anything because we use it to testing our operating system so there is not any problem with audio.
if you have an asus eeepc you can edit in a terminal this file:
sudo nano /etc/modprobe.d/alsa-base.conf
and then ad the end of this file you can add two lines below:
options snd-hda-intel model=lifebook options snd-hda-intel model=headset-mic
then you must save this file with Ctrl+X and reboot your system to enjoy your audio.