wihtout reading the other replies, I'd say that trying to decide if something you're hearing is in quarter notes or eighth notes is irrelevant, since we can't see the music and it could have been written either way. I would just try to find the steady pulse that doesn't change, boom, boom, boom, boom (like 99% of western music has a steady pulse), and figure out of it is in groups or 3 or 4. thats how many beats the measure is, and that's how we count it (say "1-2-3-4, 1-2-3-4, 1-2-3-4" or "1-2-3, 1-2-3, 1-2-3"). that gets a HUGe categorization out of the way. then almost guaranteed you'll find that the whole song is groups of 8 measures (spoken "1-2-3-4, 2-2-3-4, 3-2-3-4, 4-2-3-4, 5-2-3-4," etc.)