How do cats sustain a purr-fect purr?

Why does our hair stand up when we are scared? Does the animal kingdom experience colour differently? How do cats purr without running out of breath? Can certain types of medication cause tinnitus? What benefits does vaccination afford us? And why do some people struggle to recognise faces? Chris Smith and Clarence Ford have the answers... Like this podcast? Please help us by supporting the Naked Scientists (thenakedscientists.com/donate)