Some of the sounds are strange
It’s a good idea for an App, and the example words are useful. However the actual letter sounds are not really distinguishable enough. ‘Ц’ and ‘ф’ sound like someone opening curtains or a door opening on Star Trek, are they both ‘Shhh’ ?. And ‘з’ which should sound like ‘z’ sounds more like someone being prodded, while they were asleep. Also, I found the cutaway animation of the mouth and throat didn’t really help me. I didn’t know I had a butterfly valve in my throat, let alone how I can make it do that ! For me... showing equivalent phonetic letters in English would help more. It’s a nice idea, but needs a bit more work I think.