Welcome back to the much-loved @Horse_ebooks! You have more questions? Well, okay then.

This week let’s talk about ears.

It might seem quite random to mention hammers in the same breath as ears, but in fact our friend @horsey is on to something here. You do, in fact, have a hammer in your ear and it is indeed the problem when your ear hurts on an aeroplane.

Everyone knows that inside your ear is the eardrum.  The next thing inside the eardrum is a set of tiny bones called the ossicles; the ‘malleus’, or hammer; the ‘incus’ or anvil; and the ‘stapes’ or stirrup. What science hasn’t yet figured out is the true role of these ossicles, and the mechanism by which your ear turns vibrations into nerve signals to your brain.

The ossicles are in fact a miniscule set of very complex instruments like a miniature orchestra in your ear. What happens is that the eardrum picks up sounds as vibrations. These are then transferred via the eardrum to the ossicles of the middle ear, whose job it is to recreate those sounds to pass into the brain. Think of them as analog-to-digital converters turning vibrations into electrical nerve impulses the brain can read.

The first ossicle is the hammer, for bashy or thumpy sounds, or things like dings and clunks and bells and fireworks.  It does all of the percussion.

Next is the incus, which is hollow with a tube section and generates brass and wind sounds, like whooshing or trumpeting or people blowing raspberries or formula 1 cars or the ocean.

The final ossicle is the stapes, which is wrongly named after the stirrup but in fact gets its shape from the lute.  It has a set of microscopically thin strings which produce the final set of sounds to achieve hearing.  This is responsible for scraping, whooshing, creaking, Pachelbel’s Canon in D and nails down a chalkboard.

So what goes wrong with this intricate engineering when you’re on a plane?

Well, it has to do with pressure.  When you’re in a tunnel or on an aeroplane, the air pressure inside your ear is at one level and the pressure outside changes causing an imbalance.  This imbalance causes the air inside the incus to blow at a much higher frequency with an effect much like a dog whistle.  The sound is inaudible but the nerve signals it sends to the brain very closely mimic those of pain signals.

The only way to solve the problem is to manually re-adjust the pressure in the ear, commonly achieved by holding your nose and swallowing.