My toddler asked, 'Dad, why does the microwave make a sound when it's done?' I said, 'So you know it's finished.' He said, 'But Dad, it's a plate of hot dogs. I can smell it's done. The hot dogs have been telling me for three minutes. The smell is the sound. The smell is the beep. I don't need the beep. I need to trust my nose. My nose is the microwave's alarm clock.'