From previous thread:
sudo pacman -S sof-firmware alsa-ucm-conf
then follow these instructions and reboot:
https://wiki.archlinux.org/index.php/Lenovo_Yoga_c940#Overview
I really hate this new forum rules: close thread 3 days after last post and make it unpossible for new users to post the result of inxi -F or links. Do you really want new users?