Voloco features four effect presets:
Big Chorus -- A seven-voice harmonization effect
Hard Tune -- The classic "AutoTune" sound made famous by T-Pain and others
Natural Tune -- Gentle auto tune
SuperVocoder -- A pitched-down monster vocoder
If you hear nothing *even when a headset is plugged in*, then set More Options --> Settings --> Prevent feedback to OFF.
Voloco compresses your recordings as AAC in an MP4 container so you can easily share them.