On most days, our brains do a good job at interpreting the myriad sights, sounds, and other sensory information that bombards us from dawn to dusk. However, every now and again, even our highly-evolved minds get a little confused, resulting in what we call illusions. While all five senses are capable of tricking the brain, researchers have thus far largely focused on optical illusions simply because our vision dominates all senses. Now, scientists at the California Institute of Technology (Caltech) have devised two clever tricks that fool the mind using sound.