On my home stereo I have a spectrograph that has a 2D matrix, whereby the X axis is the frequency (deep bass on the left, vocals in the center, treble on the right), and the Y axis is the volume or power of the sound at that frequency. I have seen things like this for Ubuntu, but they work on MP3 files or other pre recorded songs. Is there anything that can do this real time for a microphone attached or simply the system mixer?
This may be a bit overkill, but Baudline is an incredible real-time FFT spectrogram. It's not in Ubuntu repos, so you will need to download it on your own. It displays a real-time analysys of source signal, but it also alows to analyse pre-recorded data. The brightness of a point represent the power of the sound at this frequency, where horisontal axis represents frequencies, and vertical time - so it kind of shows history of your signal.
It's extensive featrures make it definitelly the most advanced spectrogram available for Linux. It may be a bit too complicated for your uses, though. I am not sure what exactly you are looking for.