[LAU] JACK tool from Fons to check for denormals/NaN's/etc?

I've heard it said that the first thing to deteriorate as you get old is the eyesight. I don't remember what the second thing was. I also don't remember the name of a tool that (IIRC) Fons created, which had a very simple GTK GUI, into which you can direct a JACK stream of float's, and it lights up an indicator if there are NaN's, denormals, etc etc. I know I have it here, because I've used it. But I'm staring at the contents of /usr/local/bin, and none of these appear to be it. Can anyone remind me of the name of this useful little device? I'm trying to track down the "WOW THIS IS WAY TOO F'ING LOUD" problem in Monosynth. Thanks. (Also, on a related note, it turns out from looking at the source code that MonoSynth DOES have an LFO... it just doesn't show up in the DSSI interface, sadly.) -ken