Sound in freebsd

Firstly check which driver is suitable for your audio card.

As it is described there [http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/sound-setup.html] try to load right module: kldload snd_driver or kldload snd_hda

Information about your card can be grabbed from /dev/sndstat file or dmesg command.

cat /dev/sndstat

Installed devices:
pcm0:  (play)
pcm1:  (play/rec) default
pcm2:  (play/rec)
pcm3:  (play)
pcm4:  (play)

or

dmesg | grep pcm
 
pcm0:  at nid 3 on hdaa0
pcm1:  at nid 20 and 18 on hdaa1
pcm2:  at nid 21 and 24,25 on hdaa1
pcm3:  at nid 30 on hdaa1
pcm4:  at nid 27 on hdaa1

In my case it is Realtek ALC888 sound card and

 kldload snd_driver

works fine

To add module while system starting additional information should be added to /boot/loader.conf or /boot/defaults/loader.conf. In my case the following line should persist

snd_driver_load="YES"

Test sound card simply by command:

 cat filename > /dev/sdp

Default volume set at system boot can be set in /boot/device.hints file, for example:

hint.pcm.0.vol="50"

Although volume can also be set from command line by command mixer, example:

 mixer --without option show current volume

 mixer vol 75  --change vol to 75%