Toilet bleach: what's best, thick or thin?

Would a baby exposed to 5 languages from birth learn all of them? Toilet bleach: what's best, thick or thin? Are new varieties of fruits equally good for you? What's the proof for absolute zero? How are radio and TV audiences measured? What causes high pitched sounds in the ear that appear to come from nowhere? Join Chris Smith and Kieno Kammies for the answers... Like this podcast? Please help us by supporting the Naked Scientists