Pink Flamingos and Cochleas

I was planning to do a piece on the workings of the ear, how we hear.

The ear is fascinating.  A complex mix of cartilage and bone tunnels, moving membranes, tiny tiny bones (although still the only bones that are full size when we are born), our own amplification system, liquid filled coils, sensitive hairs and electrical impulses.  It allows us to hone in on particular noises, it can help us identify the direction the sound is coming from.  Without it our interactions with the world would be different.

And then…

Yesterday I ran a team building day.  We started with an ice breaker, an exercise in listening.  Each person had to greet another person, introduce themselves and say what they had recently watched on TV, their partner would reciprocate and then they would both move on to find different partners.  Simple enough.

Someone in the room had a secret message.  This person would introduce themselves and then say

‘The pink flamingos fly south over the artic.’

A fairly distinctive message for a number of reasons.  Once this message was passed on (it couldn’t be repeated) the person would resort to the conversations about TV programs with their next partner.

We did this for about 5 minutes.  At the end, I asked the person with the secret message to identify themselves. They all knew there was a secret message and they had to pass it on so you would have hoped they were waiting for it.   There were two of them!  What was the message?

‘The crows fly up through the clouds.’

In light of this experience (which I am sure is not unique to our team) I would like to revise my explanation of how hearing works.

Sound waves travel through the air and are channeled into the ear canal by the external auricle.  The sound waved travel down the ear canal and cause the tympanic membrane (ear drum) to vibrate.  This in turn causes movement in the three auditory ossicles, the malleus, the incus and the stapes in the middle ear.  The base of the stapes is in contact with the oval window of the cochlea.  The movement of the stapes causes the oval window of the cochlea to move and this, in turn, causes the fluids inside the cochlea to move.  This movement is detected by hair cells inside the various compartments of the cochlea.  These cells generate signals which are taken by the auditory nerve to the brain.

These signals enter the brain at which point it makes up the message that it thinks you should be hearing and directs this to the parts of your brain that should have been paying attention.

Does that sound about right?