[CM] [PD] snd

[bil at ccrma.Stanford.EDU]

That looks like it's using openGL for the graph, so you need to build
Snd --with-gl --with-motif (it might also work in gtk).  Then as Kjetil
says, get the spectrum full-window, select spectrogram in the transform
options dialog, and gray in the color/orientation dialog; it looks like
they've set the y-axis angle to 130 and maybe used the spectrum-end
scale to cut out the highest frequencies.  Once you have the 
saved-snd.scm
file, you can wrap the file part in a for-each to handle all your files
in sequence.  I think they also set the "light-dark" scale to make it
darker.