How do you deal with annoying hummers?

[Daisy Chain]

My housemate is constantly - and I really mean constantly - humming and singing tunelessly around the house. It's driving me nuts. When the TV is on, when it's not, while cooking, in the bathroom. It's non-stop wittering. I don't mean to sound horrible but it's making me crazy. How can I deal with it?

 

[David C]

Let the tyres down. Oh, wait a minute......