USB-наушники распознаются, но не работают в Ubuntu

In terminal type

alsamixer

Then hit F6 to open the menu we will use.

You may see three sections, Auto Gain Control, Headset, and Headset 1. In my case Headset 1 was muted and had no volume (red/white) in the bar. Both Headset and Headset 1 need to be unmuted and have some volume in the bar for your headphones to work.

Use the left and right arrow keys to scroll between sections. Pressing the M key unmutes. MM means muted while 00 means unmuted. Ensure both Headset and Headset 1 are unmuted (00). In my case, Headset 1 was muted.

Now use the up and down arrow keys to put volume in both bars. In my case, the volume buttons on my keyboard successfully controlled the Headset section but did nothing for the Headset 1 section which had volume all the way down. Press the up key on Headset 1 to put some volume in that bar.

If both bars are unmuted and have volume in them then your headphones should work if this was the issue. Press Esc to exit, changes will be saved automatically.