Two sounds close enough to trade places: the “v” of van and the “f” of fun. Swap one for the other and a different word comes out — this page is how to keep them apart, in both directions.
Keep the voicing on as your teeth rest on your lip at the end of the word — buzz, do not just blow.
“Teeth on lip, sì — but where is the buzz?! Keep the motor running to the end, bello — vvv, not a puff of air!”Nunzio, when he hears it
You cannot hear your own swap. That is the whole problem.
Nunzio records you reading a sentence, scores every sound in it on your phone — nothing is uploaded — and tells you which of these two actually came out. Nunzio — Accent Coach is coming to the App Store and Google Play.