(older!)

Sound setup
apk add alsa-utils alsa-utils-doc alsa-lib alsaconf

https://wiki.alpinelinux.org/wiki/Sound_Setup
default HYPPII esim jos useampi mahdollisuus, esim. hdmi vs. usb sound

vi /usr/share/alsa/alsa.conf
=
Scroll down until you find the lines that start with
defaults.ctl.card and defaults.pcm.card and put the number
(you found in the F6 context menu of the alsamixer command
for the soundcard you want as your default) at the end of
those lines separated by a space for each. For example, if
the default sound card you want is "1".
=
defaults.ctl.card 1
defaults.pcm.card 1
=
rc-service alsa restart