What do your ears have to do with getting fit? When it comes to group exercise classes, the answer is, a lot. Your fitness instructor is there to guide you through the workout, but she's also there to give you the best workout possible. That means giving you instruction on how to make things more challenging or how to achieve a perfect form that makes your workout more efficient.
If you're not listening to what your instructor is saying, it's likely that you're not maximizing your workout. Instead of zoning out during class, actively focus on what you are doing and what the instructor is saying. Make it a point to be present with your ears and you'll leave feeling more satisfied with your performance, like you weren't just going through the motions. It's another step to achieving your best mind/body connection.