At the beginning of his manuscript Humbert Humbert (the narrator and main character in VN's novel Lolita, 1955) mentions the tip of the tongue taking a trip of three steps down the palate to tap, at three, on the teeth:
Lolita, light of my life, fire of my loins. My sin, my soul. Lo-lee-ta: the tip of the tongue taking a trip of three steps down the palate to tap, at three, on the teeth. Lo. Lee. Ta. (1.1)