The Ear In Review

All about hearing, nausea and gross, gross wax

by Ashleigh Mattern

So there was a bit of a mix up in the editorial department. My editor asked for a Remedial Science “year in review” but I heard “ear in review.” Maybe it’s time to get my hearing checked.

Speaking of mishearing, have you ever wondered how we hear at all?

When a sound hits that flap of skin on the side of your head — called the pinna or auricle — it’s funneled into the ear canal, which ends in the eardrum. The sound waves vibrate the eardrum and three tiny attached bones, called the malleus, incus and stapes (a.k.a. hammer, anvil and stirrup). When we say tiny, we mean it: the stapes is the smallest bone on the human body.

These small bones and the eardrum transmit the vibrations to the cochlea, the sensory organ responsible for hearing. Shaped like a spiral shell, the cochlea contains liquid and tiny hair cells that pick up the vibrations, transforming them into nerve impulses. The vestibulocochlear nerve completes the job by transmitting the signals to your brain.

Hearing is one of the Big Five senses, but we have around 15 other senses — including balance, the second central function the ear provides. Next to the cochlea are two semicircular canals also filled with liquid and tiny hair cells. When you move, so does the liquid, and the hair cells help send a message to your brain about your position.

It’s also the reason we get dizzy when we stay on the tire swing too long, or get sick on a fair ride. That sickness happens when the liquid in your ears keeps moving after you’ve stopped.

Interestingly, this is one of the biggest problems in developing truly immersive virtual reality technology. The liquid in your ears isn’t moving, even though your sight is telling you that you are. That disconnect makes some people feel sick.

WHY DO OUR EARS POP?

That pop in your ears as a plane ascends or descends is the worst. I’ve seen people try chewing gum, swallowing, opening and closing their jaw, and closing their nostrils and trying to blow out through their nose — to varying degrees of success. Those techniques work (most of the time) because there’s a tube in the middle ear that connects to the upper throat called the Eustachian tube that acts like a pressure valve. Changing altitudes affect the pressure of the air in your ears, and opening the Eustachian tube relieves that pressure. Usually the Eustachian tube remains collapsed, but when it opens, you hear — and feel — a pop.

CAN HUMANS USE ECHOLOCATION?

Bats are one of the first animals most people think of when they hear the term echolocation. They can navigate and forage in complete darkness by generating an ultrasound (a frequency above the limit of the human hearing range) and then listening to the echoes of those calls to discern the environment around them. But did you know humans can use echolocation, too? People who are properly trained will create a sound, like tapping a cane, and be able to correctly interpret the sound waves reflected by nearby objects.

WHAT THE HECK IS EARWAX FOR?

Earwax is kind of gross: depending on your ancestry, it’s either brownish and goopy or grey and flaky. But as gross as earwax is, it actually protects the ear canal by assisting in cleaning and lubrication, and keeping out bacteria, fungi, insects, and water. That protection is why you shouldn’t clean your earwax out unless it’s causing problems. Cotton tipped applicators in particular are problematic because they can push earwax deeper into the ear, and have the ability to break your ear drum if pushed too deeply.

As for pen caps, keep them on your Bic and out of your ear. Sound good?

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HEARING LOSS MYTHS

Hearing impairment is extremely common, but even so, there are a lot of myths about the condition.

MYTH: EVERYONE WHO IS DEAF OR HARD OF HEARING USES SIGN LANGUAGE People who experience hearing loss later in life usually do not know sign language, and people who are educated in oralism (e.g. lip reading) do not always know sign language.

MYTH: EVERYONE WHO CANNOT HEAR CAN LIP READ Only about 30 per cent of spoken English is visible on the lips, and lip reading requires good lighting, a good understanding of the oral language used, and may depend on contextual knowledge about what is being said.

MYTH: ALL FORMS OF HEARING LOSS CAN BE SOLVED BY HEARING AIDS OR COCHLEAR IMPLANTS Many people use hearing aids, but others may not benefit from their use. For some people, hearing aids may not powerful enough to help, or they may not have an external ear canal in which to place the molds.

MYTH: ALL DEAF PEOPLE WANT TO HEAR While some people with hearing loss want to become hearing, this is not the case for everyone. Some take pride in their deafness, or view themselves as part of a minority group.

From Wikipedia’s article on hearing impairment.

2014-01-09