Harrison is joined by rapper and musician Kid Koala, a special guest canine, and opera singer Lindsay Michael. Individually, these experts help us find out about the delicate mechanisms that help us hear. The special guest canine helps Harrison figure out whether dog whistles really are silent, and Lindsay Michael tests out whether a person can actually shatter a crystal glass with their voice. Viewers at home find out if they have bat-like hearing!

The Big Question: "Why do people hate the sound of fingernails on a chalkboard?" 1) MY GREAT CHALLENGE: Kids must compete to see who can give our opera singer goose bumps by figuring out which material to scratch together to make the shriekiest sounds! 2) IN THE FIELD: Harrison travels to the sea aquarium and discovers that certain fish may use sound to communicate û by farting at each other!