Vocawah- Vowel Shift Filter- Guitar Effects by Subdecay
Vowel Form formant filter for Ableton live 10+ - Max Koko Music
Modor Music Formant Filter - Eurorack Module on ModularGrid
Rare Waves - Grendel Formant Filter v2.2 coming soon. This is an unusual analog filter that modifies audio input to create vowel sounds and surreal vocal-esque tones. Updates to the original include
Love Philter Formant/Vowel preset | Forum
Formant Synthesis
Kilohearts Formant Filter - PluginsMasters
Filtering for Vowels
Grendel Formant Filter | Rare Waves
Figure 2 from Interaction between source and filter in vowel identification | Semantic Scholar