This week we're exploring the science of sound and music. We sound out the human voice, hear why we all talk differently, and probe the origins of accents and the means by which impersonators mimic their victims. Also, we discover how a tune can act like cocaine in your brain and why, in some cultures, music can replace a lawyer! Also, we hear what's going on in the brains of Jazz musicians as they improvise, see how hungry sharks are similar to shoppers and find out why a big brown bat needs magnetic bat-nav. Plus, in kitchen science we discover the musical secrets of plastic bottles!