-니까 gives the ground for knowing, so this is 'now that I've heard it, I recognise it'. 들으니까 알겠다 — I get it once you play it — appears three times here, which is quiz-show talk. Note that 알겠다 is a realization arriving now, not a future tense. It also runs the other way: never having tried it, there is no way to know.