Being able to read music well enough to grasp a tune makes a huge difference.

You don't even have to learn to play an instrument (although it helps, and is worthwhile for its own sake). If you can learn enough about music to recognise the notes on the stave and understand note lengths and key and time signatures its then quite easy to copy out the tune using something called ABC, which is a way of representing music notation in text form. There are several free programs which will convert ABC text back into conventional notation, and more importantly, play it back to you.

It's not that difficult to learn the rudiments of music, and although ABC looks complicated at first it's actually very straightforward once you get to grips with it.

More about ABC here: Steve Mansfield's ABC tutorial