Tension on the true vocal cords control

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.

instead of copying and pasting things off of tests or work done on computer which im sure you did, try and read over the question carefully