For the unheard essay question, you must try and repeat the unknown piece to one of your set works. The question will already outline certain categories to listen out for such as melody, harmony and texture so that already gives you some guidelines. Try and use the knowledge you already have of your set works and relate them to the unknown piece. For example, if you hear a melodic sequence in the unheard piece, try and think of a melodic sequence you already know of in one of your set works and compare how they're similar and how they're different. Another important aspect of this question if your own initial reactions and emotions from listening to the piece, especially if the question relates to the emotions of a character in a film or something along those lines. As you're listening to the piece, jot down your reactions and then see if you can find a link there with the set works. Make sure you take notes about everything you hear when you're listening to the piece, you never know what will come in handy when writing the essay!