Comment 19 for bug 1257956

I also ran into this issue yesterday on a Dell XPS13. It is nothing Audacity specific and you can easily trigger this yourself by just running 'amixer -c 0 set "Headphone Mic" cap' or starting alsamixer, switching to the capture devices and activating the "Headphone Mic" by pressing Space on it. Similarly, you can get your headphone sound back by instead capturing from the internal mic. All in all, there is no bug anywhere. It's just that Audacity handles mics in a bad (though not buggy) manner.