IL Spectroman is spectrum analyser plugin. Insert Spectroman into the mixer track you wish to produce a spectrograph or sonograph from. A spectrograph behaves like a row of peak meters, from low to high frequencies. The louder a frequency is, the higher the bar will peak. A sonograph is a rolling display of the intensity plotted as a chart. Low frequencies are plotted on the left through to high frequencies on the right. The louder the particular frequency the brighter the trace on the screen.
This plugin is useful for checking the frequency distribution of your mix.