although this sounds similar to many previous bug reports, I couldn't find an answer in the other threads.
I have a Samsung serie 9 laptop with a single audio connector for headphones/mic. I am using Ubuntu 12.04 x86_64. When I plug a Samsung headset with microphone, the system correctly recognizes it and in the Sound Settings, the Input device changes from "Internal Microphone" to "Microphone". Everything works as it should. However, if I plug an iRig (http://www.ikmultimedia.com/products/irig/), the system does not detect that the device acts as both headset and microphone, and the sound is still captured from the laptop internal microphone. The output is, on the contrary, played back through the iRig.
I have successfully used the iRig on a desktop computer running the same version of Ubuntu by splitting the 4-pin jack into a headphone and microphone jacks with an adapter similar to this: http://www.startech.com/Cables/Audio-Video/Audio-Cables/35mm-4-Position-to-2x-3-Position-35mm-Headset-Splitter-Adapter-F-M~MUYHSFMM
I also installed pavucontrol. There I could see in the Input devices tab both the "Internal Microphone" and "Microphone" ports, but selecting ether one had no effect on the input device that is actually used by the system. I also tried with alsamixer, but could not find a way to make the external mic active.
I suspect this might be related to the electrical properties of the iRig compared to the Samsung headset. I'll be happy to submit more information if necessary.
Thank you for any help!
lspci | grep Audio 00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04) uname -a Linux giampi-samsung 3.2.0-39-generic #62-Ubuntu SMP Thu Feb 28 00:28:53 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux