Why can’t I hear right? Stephanie researches her ears.

by Stephanie Chasteen on July 12, 2010

[[NOTE:  The update on my symptoms and the resulting diagnosis is in the comments if you’re curious.  I get a lot of comments on this post asking for updates, so please look in the comments for the answer!]]

I’ve had the most distressing symptoms over the past week, which sparked my biophysics curiosity.  At first I thought that I was just groggy and out of sorts.  Then I realized that my head didn’t just feel like it was stuffed with cotton, it sounded like it was stuffed with cotton.  I felt disoriented, my head was a bit stuffy, and things didn’t sound quite right.  I was talking to my boyfriend on the phone, and I asked him, “Are you OK?  You sound really weird.”  He sounded like he had a really bad head cold.  He swore he was fine.  He sounded fine when I talked to him in person.  Talking to him on the phone later, he sounded strange again.

Ever the scientist, I realized I needed to try varying some parameters.  I switched the phone to my other ear.  He sounded fine.  Back to my left ear:  He sounded like his nose was plugged.  Back to my right ear:  Normal.  So, there was something odd about my left ear.  It seemed to be cutting out all the high frequencies.  Am I becoming deaf to high frequencies in my left ear?

Later, I go to the climbing gym.  There are many small children laughing.  The high tones in their voices sound weird, mechanical, and like they’re vibrating in the very back of my left ear.  Everything with a high pitch has a mechanical whine that sounds like it’s coming from behind my left shoulder.  Disconcerting.  Weird. And seemingly totally at odds with my observation that my left ear is cutting out the high frequencies on the phone.

I start to notice how different men’s and women’s voices differ.  Men’s voices sound mostly normal.  Women’s voices create that mechanical buzz and are difficult to listen to.  Ambient sound has similar high-pitched buzzes.  I’ve developed my own internal high-frequency monitoring device.  I’m less than thrilled.

So, I go to the doctor to find out what the heck is going wrong with me.  He’s totally gorgeous, a nice perk in the midst of my health troubles.  More science ensues.  He taps a tuning fork on the table and holds it by my left ear (the one that’s acting strangely).  I wince with the loudness of the sound.  He taps it again and holds it against the bone behind my ear.  Is it louder then?  No.  He does the same with my right ear.

Results:

  • When the tuning fork is held next to my ear, it’s louder in my left than the right
  • When the tuning fork is held on the bone behind my ear, it’s similar loudness in both ears.

So, what’s that mean?  Because it sounds the same when the sound is traveling through my bone rather than through the air, that means that there’s nothing wrong with my auditory nerve (whew!)  But it sounds different when traveling through the air, so that means that something is selectively amplifying the high frequencies as they travel from the air to my auditory nerve.

Apparently what’s wrong is that my eustachian tubes are blocked, creating a high pressure area inside the canals of my ear.  Usually I could clear my ears (getting that “pop”) to equalize the pressure, but if it’s swollen (like if you have a cold) then it’s hard to get my ears to pop.

What struck me about all this experimentation was just how much the scientific method came into play — observe, test, try changing variables, compare.  You can find out a lot just by thoughtfully testing different parameters.

The cute doctor didn’t have much to say about why this caused the odd pitch distortions, so I batted my eyes at him and went off to do my own research.

First, what about when I hear the odd buzzing amplification of high pitched sounds in the air? In that case, the sound must travel through the air to the tympanic membrane, or eardrum.  The eardrum is what transfers the sound from the air to the little bones of the ear (the hammer, anvil and stirrup).  If the eustachian tube is swollen, that restricts the movement of the eardrum.  But that seems like it would reduce my sensitivity to high frequencies, not increase it.  Perhaps, instead, the high pitched vibrations of the eardrum are somehow amplified, maybe via a resonance.  Perhaps the swollen eustachian tube has tuned my hearing to be more sensitive to higher pitches than the normal human ear?

Apparently there is a rare condition where, instead of the tube being swollen shut, the tube is left open, which allows the sound of your own breathing and heartbeat to move from the body directly to the eardrum, so you hear the amplified echo of your own voice and breath.  (Strange medical note:  A new procedure to relieve those symptoms involves placing a small piece of Blu-Tack on the eardrum to muffle the sounds.  “The Blu-Tack has to be replaced at regular intervals,” says Wikipedia.  Ugh.  I guess I could have it worse.

What about when I talk on the phone, and my boyfriend sounded like he had a cold because all the high frequencies were reduced?  In that case, I think, the sound is traveling partially through the air and partially through the bones of my skull. A dampening of the movement of the eardrum by the swollen eustachian tube might explain that (though it wouldn’t explain why the same isn’t true when I’m not talking on the phone, as above).  Or, perhaps, the high-frequency sensitivity only happens with frequencies that are not contained in my boyfriend’s voice.  Perhaps some high frequencies are being amplified, and the rest are cut out?

Obviously, I haven’t managed to find an ultimate answer to my queries.  If anybody has any ideas, or insider knowledge, please share.  This has made me very curious.  If I’m going to be suffering, I might as well learn something new about my body!


Image: Perception Space—The Final Frontier, A PLoS Biology Vol. 3, No. 4, e137 doi:10.1371/journal.pbio.0030137 ([1]/[2]), vectorised by Inductiveload

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