If you receive this error: "Error opening sound device. Please check the input device settings and the Project Sample Rate" or "Please check the output device settings and the Project Sample Rate" even when no other device is using the sound card, and your permissions are correct, it simply means there's a problem with your Audacity settings. You may have a sample rate selected that your sound card does not support. You can alter this by changing the Project Rate at the bottom left of the Audacity window. If you receive the "check the input device settings" message, try setting the "recording channels" in the Audio I/O tab of Preferences to mono or stereo, and if you are recording something playing on the computer, turn off "software playthrough".
If you are having issues, try a newer Portaudio snapshot: clear audacity-src-1.2.x/lib-src/portaudio-v19/ download pa_snapshot_v19.tar.gz from http://www.portaudio.com untar into directory mentioned above go back to audacity-src and run ./configure..., make, make install again Please post your experiences with Audacity and PortAudio v19 directly to Audacity_PortAudio_v19. As noted there, known issues currently exist with v19 if playing audio with OSS emulation enabled under ALSA.