Just wondering has anyone ever used one of these for wah type effects? It's a bit scarce now, I found one in my stash, never got around to using it, a guy I knew used one in his diy "hoot-wah" which was a wah pedal circuit using the MF8CCN, driven by a PVC hose attached to a rubber bulb, there was a pressure transducer to convert air pressure in the bulb to a voltage and eventually control the MF8CCN. You would put your foot on the bulb (a bit bigger than a golf ball) and push down on it to control the wah. This was near 20 years ago. It was capable of extreme wah sounds, as in high Q/very narrow pass band, but I liked the more sane settings on it.
MF8CCN datasheet (http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS008694.PDF) I see they are still available, but in large lots more than likely.
I was thinking a pair of them might be good for a "talking" wah pedal design, with the center freq adjustable by a clock (or oscillator) and the Q programmable. Capable of 4th order filter if required. A microcontroller could control the two formants in a non-linear fashion for some real nice tones perhaps, as recently suggested by R.G. Or maybe there is a more modern replacement for this chip these days?