I've had a lot of problems with my microphone when I try to use it with Skype on Linux Mint (which is based on Ubuntu). Do you have the PulseAudio Volume Control installed? If not then install it. With the recording software open go to the "Recording" tab in PulseAudio and try playing around with the sliders. You may need to unlock them and set one side (left or right) to 0 while leaving the other one recording.