>"The C sound doesn't involve the tongue" In [this](https://i.imgur.com/sAG0Mz2.jpg) diagram and [this](https://www.youtube.com/watch?v=n4Y4EQaw5oU&ab_channel=BeckmanInstitute) x-ray video is explained how the C sound is created by the tongue and pallate. I'm pretty sure that all letters can be pronounced with relaxed speech muscles, even glottal sounds such as /O/.