Timeline plot of amplitude spectrum

I have a project in which I have to plot in real time the audio amplitude spectrum (from the microphone) for a couple of hours in real time. I started to modify the Matlab example demoai_fft. I removed everything which is related to the magnitude spectrum and I designed the new axis where the timeline plot will be placed. Can you tell me how to start to implement this? Virtually, the plot must resize in time in order to be displayed in the axis. Thank you very much!