Demonstrating synthesis of vowel sounds using the Grendel Formant Filter Eurorack module. This 100% analog filter allows voltage-controlled selection of English vowels from a 2-dimensional map. The map corresponds to the International Phonetic Alphabet vowel chart, a.k.a. the vowel trapezium.
In this video, an analog joystick with X and Y CV outputs is used to control the filter module. Two channels of MIDI-CV converter may also be used. The module is designed to accept CV sources with 5 volt range. Either -2.5 .. +2.5 volts or 0.. +5 volts can be used for optimum control. Wider CV ranges (up to +/- 10V) will not cause damage, but should be attenuated for best articulation.
Visualizations were made with a Tektronix TDS 350 digital oscilloscope in XY display mode, 1 volt per division.
The Grendel Formant Filter is made by Rare Waves (Austin TX)