How do electronic blow out candles work?

[Mortimersun]

Ok, this might be a peculiar question, but I was having a discussion with a friend about those blow on/blow off candles and how they work. We both have our own theories and of course I think I have the most logical one, so I thought I’d ask you guys what your opinion is. What do you think the mechanism is behind the electronic candles to get them blown out?

[lazypan]

Sound sensor? I have a set from Philips which you have to turn upside down in order to turn them on or off. Which means there’s a motion sensor in them probably.