ALSA Utilities

Install the alsa-utils package. This contains (among other utilities) the alsamixer and amixer utilities.

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pacman -S alsa-utils

Unmuting the channels

ALSA by default has all channels muted, all of which will need to be unmuted manually. This can be done using amixer:

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amixer sset Master unmute

This can alternatively be done using alsamixer:

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alsamixer

Test your changes

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speaker-test -c 2

User privileges

Usually, local users have permission to play audio and change mixer levels. To allow remote users to use ALSA, you need to add those users to the audio group.

参考：https://wiki.archlinux.org/index.php/Advanced_Linux_Sound_Architecture