Receptivity, hearing loss and dancing hairs in your ear

Hearing is such a wonderful sense. We forget how unique it is. Until we lose it. I have several family members whose hearing is severely damaged because of exposure to loud noises. In those days farmers didn't use ear muffs so machinery and the firing of shotguns did irreparable damage to their hearing. The effects of this often only show themselves in later years. It is particularly hard to learn these vital lessons when the effects are not immediate. My eldest brother returned from a punk rock concert forty years ago, where he had been standing a little too close to the wall of enormous speakers at the event. For three days he had a ringing sound in both ears and it lasted long enough that he thought permanent damage had been done - it wasn't, he was lucky. Who would've thought years later that the very headphones we use to protect the ears of workers are now damaging the ears of our young who blast themselves incessantly with load music. 

We lose your hearing in many different ways and for many different reasons. Conductive hearing loss is when there is a problem in the transmission of sound to the inner ear. Wax and ear infection or middle ear ossicles (when the tiny bones transmitting the vibrations on the ear drum can no longer do their job) can all contribute to this form of hearing loss.  It is sobering to think that the ear drum which is the fragile link between the outer ear and the middle ear is only 10mm in diameter.  However small that appears, the drum thickness is tinier still at only 0.08 mm.  It can be easily ruptured by excessive noise, pressure or physical trauma.  For those among us who insist on jamming ear buds in their ear to clean them - remember a typical sheet of paper is thicker than your ear drum.  Hearing is a sensitive business from every point of view.

This fragility is matched by the bones, the ossicles, which are on the other side of the ear drum resting against it to pick up the vibrations of the drum. The ossicles are the three tiniest bones in the whole body and form the coupling between the vibration of the eardrum and the forces exerted on the oval window of the inner ear.  This system is connected to the cochlea which looks a bit like a shell.  It has tiny hairs inside that vibrate and transmit the sound to our nerves in the brain.  Usually, age related hearing is when these tiny hairs become damaged and die off.  Our high frequency hair cells die off before low frequency ones and we lose some every year.  If you want to see what these hairs look like, check this out.  You need to press the video button to actual see the hair dance to music.

If you have ever wondered how it sounds to have a cochlea implant you can experience it here (click on link below and listen to both tracks).  I must admit I was disappointed with the results but then my expectations were high.  If you cannot hear at all then this must seem like unbelievable progress.  For Beethoven losing his hearing must have been a torment almost impossible to endure.

https://auditoryneuroscience.com/prosthetics/music

To see how wonderful these implants can be for those experiencing deafness this young boy's face says it all.

It is startling to discover that the young generally are more receptive.  They literally hear a much broader frequency range than older people.  Another fascinating feature is that if you lost 166,000 photoreceptors in a retina of your eye you would not be able to see a patch in your vision smaller than the moon’s image.  Everything else would look okay. However, destruction of 166,000 hair cells in your ear would result in disequilibrium and profound deafness.  

We need to respect this sense so much more than we do at present.  Think of an inertial guidance system, an acoustic amplifier and a frequency analyser inside the volume of a marble and be impressed.  Hair cells detect motions of atomic dimensions and respond 100,000 times per second.  

Remember that over time, repeated exposure to loud noise and music can cause hearing loss. To put that in perspective we need to know a few facts.

1. The decibel (dB) is a unit to measure the level of sound.
2. The softest sound that some humans can hear is 20 dB or lower.
3. Normal talking is 40 dB to 60 dB.
4. A clap of thunder from a nearby storm (120 dB) or a gunshot (140-190 dB, depending on weapon), can both cause immediate damage.
5. A rock concert is between 110 dB and 120 dB, and can be as high as 140 dB right in front of the speakers.
6. When listening to a personal music system with stock earphones at a maximum volume, the sound generated can reach a level of over 100 dBA, loud enough to begin causing permanent damage after just 15 minutes per day!

But it is the effect that this sense can have on our spirit that surprises me constantly.  Just as we can damage this amazing organ with abuse, when used appropriately it be transformative.  I love these quotes on what music can bring to all our lives.

“..although sounds are but vibrations in the air which affect the ear's auditory nerve, and these vibrations are but chance phenomena carried along through the air, even so, see how they move the heart. A wondrous melody is wings for the spirit, and maketh the soul to tremble for joy.”

`Abdu’l-Bahá

“Music produces a kind of pleasure which human nature cannot do without.” 

Confucius, The Book of Rites

Owl Puke

Well it has been a week of discoveries!

For example today I was rounding up my two-week science teaching of middle school lab work with a video of the barn owl.  We have been covering body systems and had started with the skeleton.  Much making of full sized black cardboard skeletons with labelled bones tied together with wool or paperclips.  In fact my entire science lab resembles a bizarre Hallowen celebration with many of the black shapes running on the walls, spread-eagled on corridors or waving frantically from a board in the classroom.  We then moved on to dissecting an owl pellet.  It was tricky justifying the expense of purchase of owl vomit in these economically challenging times, but I got it.  As owls cannot digest the bones, feathers and fur of their prey they vomit it up in these pellets so I reckoned that would be a creative way to allow them to pull all the bones out and reconstruct the victims of the owl.  Various parts of rodents, voles, birds, shrews etc were all carefully extracted from these solid lumps and then separated out into piles of each respective animal.  The lab echoed to excited cries of  “I’ve got a skull here!”, or “This is a pelvis of a rat” and they grew expert at identifying shrew skulls because the tips of their teeth are red.  Tweezers and heads bent over dead piles of bones has been our points of interest for some time and now all bones have been stuck on black card board and identified.  The corridors have been full of conversations like, “what did you find in your owl puke?”  After all these experiences I decided to close the topic with a series of videos showing owls vomiting up their owl pellets, in flight catching prey and finally one of an owl swallowing a huge rat.  So it was with complete despair, while watching them, I heard a group of students crying out, “that is so gross, what is that lump coming out of its mouth?” or comments to that effect.  At which point, several of the brighter students turned and exasperatedly pointed out that we had been dissecting owl pellets all week and of course that was what these were.  Several students looked green around the gills that they had been rummaging around in these horrid looking turds and were outraged.  At this point all my satisfaction about my lesson plans and lab work drained away.  I should have remembered when you take kids into labs a part of their brains switches off and goes into a sort of “Bunsen burner, test-tube, chemical, mesmerised state” that closes down all rational thought.  If I entered the lab and began a strange witch doctor ritual with feathers and skinned rabbits around my head it would make no difference.  You can tell, when they approach you in the lab and ask, “can we blow something up next week?”  Everything but explosions to sixth grade is a complete waste of a lab session.  Here is the owl video, be patient – it is taken by amateurs discussing their camera storage capacity.

But for me the most beautiful part is watching these birds in flight – this is 6 minutes long so don’t feel you have to watch it but there is something angelic about their flight in slow motion that grabs me.  Okay the last part is fairly gross!

It is all a learning experience.  From the sublime to the ridiculous, this life.  One minute you think you are running exciting educational science experiments the next you realize it really is just all vomit.  There is a metaphor about life in that last line.  Education is just about regurgitating stuff and life usually involves vomit for some reason!