Jenny Diski has written recently about being treated like an old bag for complaining about her young neighbour’s music. I sympathise, but wonder how much worse she would feel if she lived in Latin America. When I came to Nicaragua seven years ago, I briefly lived next door to a man who had to get up very early to go to work. His house was made of plastic and tin, but equipped with a powerful radio which he put on at full blast at 3.00 a.m. every day except Sundays.

There's a kind of hum all over the world. But only some people can hear it. It turns out not to be aliens – though I don't see why aliens wouldn't hum as they went about their world-conquering. Sometimes it's from local factories, electricity wires, fridges, or in my case a nearby airport that emits a thunderous roar when they're testing engines. All these things hum officially and it's not hard to find the source, not as hard as tracking down the humming aliens. But in two-thirds of cases, there's no obvious cause, and it has been decided that if you can still hear the hum you're suffering from vicious-cycle over-sensitive hearing. I think we may be on the verge of a new syndrome.