This is a text search app. It is intended to be turned into a tool for teachers to use to scan through written work / test answers. You can choose a question from the drop down over to the left, then either select a search term from the drop down below it or type one into the text box. Search for letters, punctuation, common misspelt words... anything that might be useful for teachers. Press the green magnifiying glass icon to begin the search. You can make notes about each question / answer in the textarea on the left.
Skip through the search terms using the blue buttons and reset the text back to normal by pressing the red button with the recycle icon. You can also change the highlight colour by using the colour input (works best in Chrome i.e. you actually get a colour pallette to choose from).
I've always thought the point of this question was: if there's no way to establish whether there was a sound, then it ultimately doesn't matter. In fact, you could say that the definition of a sound is its detection, rather than the physical phenomenon. Of course, once we develop an instrument that can detect vibrations we couldn't otherwise hear, a previously non-existent sound comes into being.
Sound is something within human experience. Outside of this it's just air (or whatever other medium) vibrating. If someone is there to hear it, it makes a sound, if not, it causes rapid movement of particles.
We do not know if our actions are controlled by a causal chain of preceding events (or by some other external influence), or if we're truly free agents making decisions of our own volition.
Quantum mechanics makes this problem even more complicated by suggesting that we live in a universe of probability, and that determinism of any sort is impossible.