In 1981 it was only a theory – one that seemed to go against all logic. The theory said that if you have a signal – say, a sound that was too weak to be heard – adding a little noise would make it easier to hear. If you added too much noise, you would drown out the weak signal. Add too little noise and it wouldn't help at all. But when you add just the right amount of noise, a sound signal too weak to be heard could be heard.

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