in Yamaha FS1R

Fun with Formants: Vocal Sounds with Crystal

Crystal is useful for making synthetic sounds that don’t occur in nature. If instead you want truly human vocal sounds, you’re probably better off with a sampler. Although, even with a sampler, realistic human voices are notoriously difficult to achieve. In this tutorial however, we’re aiming to get synthetic sounds with a vowel-like character.

Nice tutorial from the developers of Crystal VST.  Relevant for FS1R.