From the ALSA wiki
ALSA is unfortunately both rather complex and underdocumented. Therefore there are resources like this Wiki to help people.
This section is about the steps needed to make sure your ALSA setup works. There are other ALSA setup issue fixing pages, as part of the official ALSA documentation, and this section supplements them.
If you hear no sound
Check the sound drivers for your card are active
First check that the ALSA drivers are installed and have recognized your card: Make sure that /proc/asound/cards lists your card, as card number zero. If not, make sure that the appropriate driver module is loaded. To figure out which modules you need, use the lspci | egrep audio command. This usually will list the name and type of your sound chipset. The main ALSA website then contains a list of those chipsets and the required drivers. As a wild guess, for most recent low cost AC97 based motherboards and laptops, try the snd-intel8x0 driver.
Unmute the appopriate mixer channels
If your card's driver is installed and its name appears in /proc/asound/cards, and you still hear no sound, the most likely cause is that you haven't unmuted the right mixer channels and set their volume to nonzero. Note that ALSA sort of misnomes the channels of the mixers of many cards. Use 'alsamixer' to play around with the settings of the most obvious sounding channels. There are often descriptions of what the channels are in the AlsaDrivers section about specific sound cards.
Check whether your application uses OSS instead of ALSA
If you still hear no sound, your application may be set up to use OSS. Check with your applications preferences to see if this is the case. The best fix is to set you application up to use ALSA instead of OSS. If your application does not support ALSA, there are three possible solutions:
* Make it use a sound server that uses ALSA for output. * Load the OSS compatibility modules for ALSA. * Use the aoss wrapper to run the application.
Details on OSS emulations are provided in the OssEmulation section.