After installed Void, I needed top configure the audio setup.
To do this I first installed the alsa-utils package:

sudo xbps-install -S alsa-utils

Then I added myself to the audio group:

sudo usermod -a -G audio eamoc

To find out what the active audio interface is, do:
cat /proc/asound/modules

This will display the module order in the kernel:

➜ cat /proc/asound/modules
 0 snd_hda_intel
 1 snd_hda_intel
 2 snd_usb_audio
 3 snd_usb_audio

To configure my system correctly, I create a file .asoundrc in my home directory.

vim ~/.asoundrc

It turns out that on my system, the interface that I want to use is number 3, so I go:
➜ cat <<EOT >> .asoundrc
defaults.ctl.card 3;
defaults.pcm.card 3;
EOT

Then I reboot