There's no need to upgrade the kernel (and in fact it isn't recommended as it
isn't supported by Trisquel's developers). Just upgrade Alsa modules as
described here:
https://wiki.ubuntu.com/Audio/InstallingLinuxAlsaDriverModules
In short, open a terminal and type:
sudo add-apt-repository ppa:ubuntu-audio-dev/ppa
sudo apt-get update
sudo apt-get install linux-alsa-driver-modules-$(uname -r)
Then reboot the computer.
(This needs to be done for every kernel version so it is best to wait a few
days before upgrading to a newer kernel as the Alsa module might not exist
yet in the repository.)
