What is the scientific word for speech?

Answer 1

This question is too vague but I will answer it as best I'm able. If you are referring to the actual act of speaking words then it is called the manner of articulation. If you are referring to the audio waves present in the air generated by speech, then you might be looking for phonology in which these units of sound are called phonemes. On the flipside of that if you are referring to the understanding of these audio waves then it is phonetics and these units of sound are called phones. This is why it is called a telephone - it is a method of transmitting phones via telecommunication.

Answer 2

"Tongue" is that thing in your mouth.