Voice FX is a program I wrote in the mid-90's and that was distributed by Synoptic. Here is some advertising text, as it appeared on Synoptic's web site.

Transform your Voice with Voice FX, a program with a fun and user-friendly interface. Record your voice or load any sample file and apply amazing effects.

40 effects, developed with the help of Virtual Waves 2 from Synoptic, are available, with a simple mouse click. Of course you can apply several effects on the same sound to get more complex results. A lot of samples are already provided with the program.
Voice FX is the ideal tool to create techno voices or to generate amazing sound effects.

VOICE FX

The 40 Effects of Voice FX:

Acoustics
Airport, Cathedral, Bedroom, Bathroom, Tunnel

Aliens
Creature, E.T., Martian, Monster, Reverse

Delirium
Stammering, Hoarse, Sick, Shaked, Under Water

Echoes
Speed Up, Speed Down, Classic, Reverse, Mountain

Filters
Closing, Opening, Low-pass, High-pass, Resonant

Robots
Android, Cyborg, Electric, Machine, Vocoder

Transmissions
Jamming, Cut-up, Flanger, Mix-up, Interference

Volumes
Bell Curve, Fade In, Fade Out, Percussive, Tremolos