In order to get sound out of your FreeBSD box, you'll need to either load your sound driver module or compile sound support in your kernel -- it's not installed by default. For this you need to use kldload to load your sound driver. If you don't know which sound card you have -- and therefore don't know which driver to use -- you can load the generic snd_driver module (in 5.x systems -- in 4.x you need to load the snd module), which works for most cards, like so:
samizdata# kldload snd_driver
If that works, you'll probably want it to load automatically at boot time. To do so, you'll want to append a line about snd_driver to your loader.conf:
samizdata# echo snd_driver_load="YES" >> /boot/loader.conf
And presto, when booting, your system will always try to load snd_driver.
FreeBSD5.4 and above Sound
Since 27/07/04 the sound system has changed a lot and now to install sound under FreeBSD you have to do the following:
freebsd# kldload sound
Then find out your sound card. I'm using an ASUS A7N8X motherboard with Nvidia onboard sound so I typed
freebsd# kldload snd_ich
Too find out what driver will work with your sound board/chip have a look at the NOTES file in /usr/src/sys/conf/NOTES
search for 'snd' and you will find descriptions of all the different sound drivers.
Then when I had tested this and it worked I entered the following into my kernel:
Add the following lines to /boot/loader.conf