[2023] Introduction sound track don't stop on 1.9.2.1(Lance)

As this is happening, alt-tab out of the game . Right click on the Speaker icon in your Windows task bar, open Volume Mixer. If you see the Steam Webhelper in there, mute it.

If that helps, this is a Steam problem in my opinion, caused by their radically new client that installed recently.  

What I described was a Windows function, not a Steam one; muting that particular Steam process in the Windows sound system. TBH I'm not sure of the Mac equivalent, even though I'm a Mac user myself.

I can see several Steam helper threads in Activity Monitor but no way to mute them.

This is the best I could find with a quick search

How To Mute The Steam Web Helper On Your Mac – LEMP

lemp.io  

Never noticed that option in Steam before, perhaps it is new with their new client. Odd that muuting the Steam webhelper in Windows does stop this problem.

Did that in fact help?