We are so used to speaking and listening that we don’t often think about what speaking is. It is simply making vibrations in the air that are then transmitted to others around us. A microphone is one way to pick up these vibrations and a speaker, which is designed to recreate those vibrations can play the sounds back.
But pianos make sounds don’t they? They are not just for music. If we hook up a machine which can play just the right notes at just the right time, and for the right amount of time, we can get a rough approximation of speech. It is surprising at first, but when we realise that it is just really a way to approximate the sound waves made by people, we can understand how the feat is accomplished