Thought Experiment: We have studied the open-closed resonator in air. Let's turn our focus to other gases: helium (He) and sulfur hexafluoride (SF6). Helium is lighter than air. SF6, on the other hand, is heavy, almost 5 times heavier than air. How would each gas's speed of sound compare to that of air? Higher? Lower? The same? How do you expect the resonator to react in each gas?