Tympanometry On an Autumn Day in April

Today, I have to study for, and take, an exam on Tympanometry. I do not want to study.

I want to sleep. And before sleeping, and after sleeping, and in between sleeping, I want to lie there and think pleasantly about inconsequential things.

Tympanometry is the study of the compliance of the eardrum. The author of my textbook is a charmingly pedantic person who cannot resist pointing out that when we refer to a drum, we don't just refer to the stretched skin over the head of the drum but also to the space behind it, enclosed within wood, the resonating chamber. Therefore, the author of my textbook says, we should more properly call the eardrum the "eardrum membrane."

No one will ever do this.

There are several important things you can measure about the eardrum membrane. It is a gate which allows some to pass and denies others; when it passes acoustic energy into the middle ear, this is called admittance. When it opposes the movement of acoustic energy, this is called impedance. Once upon a time, someone coined the portmanteau word "immitance" to describe these two things together: what is admitted, what is denied.

I do not want to study the four types of basic immitance tests and their eight purposes. I want to sit in my chair and look out the dirty window into my badly-tended yard, which is miserable today with wind and rain and gray clouds so low they could almost roof your house. I would sit there with a book of poetry in my lap, and read a poem every now and then, and then look out the window for awhile, not thinking about the poem, and then turn a couple of pages and read another one.

Tympanometry measure the compliance of the eardrum: how willing is it to move when you push or pull on it by manipulating the pressure in the ear canal. If I were an eardrum, I would not be compliant at all. "What type of tympanogram are you?" would make a terrible internet quiz, but my answer would be: Type AS. I am shallow and stiff. I have low compliance. It is possible I represent ossicular fixation. That would hardly surprise me.

The ossicles are the bones of your middle ear. You were taught to call them the hammer, the anvil, the stirrup. They are the smallest bones in the human body, in particular the stirrup, which I have learned to call the stapes as I have become inculturated to the language of my field. So many common, everyday words replaced with jargon. Earwax, eardrum, hammer and anvil, ear; ceruman, tympanum, malleus and incus, helix, concha cavum, triangular fossa.

There is a poetry to it, all that latin. I'm not sorry to be learning it, except today, when I don't want to be learning. Perhaps I am a Type B tympanogram. I am an eardrum with no compliance at all. I may be perforated, or diseased.

I can tell you the normal volume of the ear canal in both adults and children when measured at 200 decaPascals of air pressure. You might not think this matters, but it does. It is diagnostically significant. But I don't care much about that today. I can tell you, too, that the goldfinch I can see through my dirty window, enlivening my depressed front yard with his ready-to-mate springtime brilliance, weighs about half an ounce. We may be proud of the tininess of our stapes, our stirrup, 3 millimeters from end to end, and the precise way its footpad rests in the oval window of the cochlea, ready to pass on--not only pass on, but to amplify--whatever acoustic energy has made it past the bouncer at the door of Club Eardrum Membrane. But I bet that goldfinch's bones would put our ossicular chain to shame.

Were you surprised to hear me say the cochlea has a window? It has two, actually, the oval window and a round one as well. It is like a hobbit house in there. There are round windows in my bird feeder, too, not the thistle feeder the goldfinches love so much but the other one, that usually has sunflower seeds and millet and the occasional peanut. A cardinal is there now, poking his beak into each of the round feeder ports, circumnavigating the feeder on its circular perch. He always hopes to find something better in the next round window, but he does not. They all have the same thing in them. They are all empty. Both the dirty window and my eadrum membrane admit the sound of the brief, irritated chirps he makes each time his beak comes up empty. He goes around twice, just to be sure, and then flies away.

When I leave to take my exam, I will first fill the feeder from the bag of seed mix I keep in the garage, and the cardinal will come back, all forgiven. The birds' love for me, for my yard, lasts only as long as the seed does, and then it quickly turns to anger or indifference. But it turns back into love the moment the feeder is full again. If they were eardrums, they'd be highly compliant. They are easily moved.

Yesterday one of my children killed a mouse by hitting it with a stick. One of the cats had caught the mouse, and I believe my son thought he was being merciful. Perhaps he was being merciful. It's so hard to say. One mouse, taken up by a cat, escapes to live whatever span of life a mouse is given. Another, broken somehow inside, can only die. It is impossible for us to know which mouse our son killed, the blessed mouse, the mouse upon whom Providence smiled that day, or the doomed mouse, the one whose small limp body I would have taken up later and, with regret, laid down again in an out-of-the-way place to fulfill its next destiny. A cat cannot be blamed for acting in accord with its nature; a mouse, whose kind have always produced enough progeny to feed the owls and the cats and the smaller hawks and still leave the world with more mice than it started with--well, what I mean to say is that a mouse cannot bear the weight of too much grieving.

Now a dark-eyed junco is pecking at the ground under the feeder, scavenging for fallen millet. I love these birds with their deep gray above and clear white underneath, and I never see one without wishing to hold it, to feel its small body rest between my palms. I would never hurt it. I would take as much pleasure in letting it go as I had in scooping it into my hands in the first place.

But I will never hold a dark-eyed junco unless it's injured, unless we find it unmoving but still breathing under the window or carried into the breezeway by a cat. I know how to make an injured bird a nest in a small box, and where to put the box to keep it warm. I know what it is like to come check the box to find the bird standing up, peering at me with sharp intelligent eyes, ready to fly again, and I know what it is like to find it still and cold. I know that there is little you can do for the injured bird besides keep it safe from opportunistic cats, and, perhaps, children a bit too eager to dispense mercy.

The first step in any examination of the ear is otoscopy, peeking into the ear canal to check for ear wax, bugs, beans, plant life, infection. A healthy tympanic membrane glows a pearlescent pink, and it refracts the beam from your otoscope into a cone of light that is not an intrinsic part of the eardrum but is nonetheless a beacon declaring that all is well. I have never seen the cone of light for myself; only pictures. But I know that one day I will.

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