Binaural fusion is when two different sounds go into both of your ears, but your brain makes it sound like it's only one sound. It's like when you see two different colors, like blue and yellow, but your eyes mix them together to make green. Your brain does the same thing with sounds. It puts the two different sounds together so it seems like it's only one sound. This helps you hear better and figure out where sounds are coming from. It's like a superpower that our brains have!