環境
PC : Lenovo Thinkpad T14 Gen1 AMD
CPU : AMD Ryzen 7 4750U
RAM : 48GB
OS : Ubuntu 20.04
Kernel : 5.4.0-53-generic
解決策
下記を実行して再起動
sudo add-apt-repository ppa:hui.wang/pa-testing
sudo apt install libasound2
参考
https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1901157/comments/12
https://askubuntu.com/questions/1291047/dummy-audio-on-thinkpad-t14-amd