The long abandoned Vocaform formant synthesizer for iPhone has been updated for iOS 7 as a new Vocaform 2 app. Vocaform 1 originally came out in 2009, but has been neglected since early 2010. The developer hasn't posted any demos yet for the new app.
Vocaform 2 iTunes Description:
Vocaform is a polyphonic formant synthesizer for iPhone. It mimics resonant body sounds such as a voice or stringed instruments. The tone ranges from eerily haunting to gritty 8-Bit noise. A wide variety of additional sounds can be created with the included digital audio effects.
Vocaform 2 has been completely rewritten for iOS 7. It features a new polyphonic audio engine and a beautifully simplified interface.
- Effects: Multi-Tap Delay, Filter, Auto-Vibrato, Chorus.
- Two pitch bend modes.
- XY-Pad and Vertical Key touch control parameters.
- ADSR envelope.
- MIDI Input from external USB keyboards.
- Virtual MIDI from 3rd party iOS sequencers.
Update: thesoundtestroom put out a timely demo video for this new app!