MARY LOUISE KELLY, HOST:
This next story is personal. As you know, my job is to ask people questions and then listen. And it's radio, so your answers, your voices - that is everything. But a few years ago, it started to feel like everyone was mumbling, and I realized I was losing my hearing. I spoke about that with NPR's Manoush Zomorodi of the TED Radio Hour.
(SOUNDBITE OF ARCHIVED NPR BROADCAST)
MANOUSH ZOMORODI: Do you remember when you started losing your hearing?
KELLY: I was 42. I had just published a book. I was on book tour, and it became apparent at event after event I couldn't hear the questions. After a while, it just becomes embarrassing. And I realized, I should go get this checked out. And I did. It was humbling in part because I still, to this day, can pass with flying colors the little minimal hearing tests that we all get with an annual physical where they say, you know, raise your hand if you hear the beep. I can hear the beep. What I can't do is distinguish between consonants. No matter how loud the volume is, I can't make out words anymore.
And when I went to the full workup at the audiologist, they did a test with me. And they said, I'm going to say a word. Just repeat the word. And I said, OK. And it would be park bench. And I would say, park bench. They would say, skateboard, and I would say, skateboard. And they would say, purple, and I would say, purple. It was fine. I didn't do great, but I think I got something like 7 or 8 out of 10. And then they repeated it - the same test...
Park bench. Park bench.
...But holding just a piece of printer paper...
Skateboard.
Skateboard. ...Up in front of their lips so that I could not see the audiologist's lips move.
Purple. Purple.
And I think I got 3 out of 10. And I realized how much, without even realizing it, I had come to rely on being able to see somebody's face, being able to see their lips move. And when I can't do that, I really can't hear. And they told me I had severe to profound hearing loss, particularly at higher frequencies, which means I was missing an awful lot.
ZOMORODI: And so you got hearing aids.
KELLY: I got hearing aids, and that was a revelation. The first day I got them, everything was so loud in ways good and bad. Good ways - I'd kind of forgotten pop music had words, and I was bopping along, singing and thinking, I haven't actually heard what they were saying in I don't know how long, but it's been awhile. I was driving my kids around just doing school carpool, and I realized they're chattering away, my children in the back seat. And it had just been this hum. For years, I hadn't been able to hear what they were saying, and now I could listen to them. I mean, what a moment of joy.
On the flipside, I remember the first time I walked into Starbucks with hearing aids, and I burst into tears and had to walk right back out because it was so loud. I hadn't heard the coffee grinders in their full glory for years, and they're really, really loud. And so there's an adjustment as your brain relearns how to process all of those sounds and help you make sense of them.
ZOMORODI: Depending on how we hear, the world can be a totally different auditory experience for each of us. And Mary Louise's hearing loss is actually pretty common.
JIM HUDSPETH: In our society, about 10% of the populace - that's 30 million people - have significant hearing problems. By the time that we're on the order of 70 years old, about a quarter of us have significant hearing loss. And by 80, it's more than half.
ZOMORODI: This is Jim Hudspeth.
HUDSPETH: I'm a professor at Rockefeller University in New York City, and I'm a neuroscience researcher. So I work particularly on hearing.
ZOMORODI: And Jim says to understand why hearing loss is so common, we need to understand how the ear works.
HUDSPETH: Sound is, of course, a vibration in the air. And that's really obvious when a jet plane, for example, rattles a window.
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HUDSPETH: There's energy or power flowing through the air. Sound energy hits the eardrum. It moves three little bones in the middle ear. And finally, it causes pressures to change in the spiraling cochlea. That's our organ of hearing. The cochlea is about the size of a chickpea, a garbanzo bean. It's a little thing. There's one in each ear. And within the cochlea, there are 16,000 sensory receptors. They're called hair cells.
ZOMORODI: Jim continues his explanation from the TED stage.
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HUDSPETH: Now, these hair cells are unfortunately named because they have nothing at all to do with the kind of hair of which I have less and less. These cells were originally named that by early microscopists, who noticed that emanating from one end of the cell was a little cluster of bristles. With modern electron microscopy, we can see much better the nature of the special feature that gives the hair cell its name. That's the hair bundle. It's this cluster of 20 to several hundred fine, cylindrical rods that stand upright at the top end of the cell. And this apparatus is what is responsible for your hearing me right this instant.
Those little bristles get tickled or moved by the sound energy. And when that happens, the cell develops an electrical response...
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HUDSPETH: ...That it then communicates to the brain. So that's all the brain knows. These 16,000 cells each send information about a particular sound that flows into the brain. And the brain then says, OK, I heard a middle C.
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HUDSPETH: I heard whatever tone it happens to be.
ZOMORODI: And so what exactly is happening in Mary Louise's ear, for example - in all our ears - when we hear and then when we lose our hearing?
HUDSPETH: Basically, any noise that's loud enough to be uncomfortable, to make your ears hurt, is doing some damage to the cells of the ear.
ZOMORODI: Oh.
HUDSPETH: The little hairs no longer actively amplify the incoming sound, and therefore, hearing becomes harder and harder - consonants, for example. So the difference between buh (ph) and puh (ph) and things like that is somewhat subtle. And the high frequencies that are necessary to convey that information are the first thing to go. And so one begins to have trouble understanding speech. And then as lower and lower frequencies are affected, the difficulties become greater and greater.
ZOMORODI: What have you observed about your own hearing over the years?
HUDSPETH: Well, the principal thing, as I've observed, is I was stupid in the 1960s.
ZOMORODI: (Laughter).
HUDSPETH: But then, so was everybody. So I spent much too much time at loud concerts or with my head between two speakers turned all the way up, and I'm paying some of the price of that now.
ZOMORODI: That was you in the '60s. I'm thinking of me in the late '80s, going - sitting front row at a Guns N' Roses concert and having that ringing in my ears for three days afterwards and - big mistake.
HUDSPETH: Yeah. It's worth it to hear Slash.
ZOMORODI: (Laughter).
HUDSPETH: But I agree. You know, if that's the last thing you hear, you might rue the experience.
ZOMORODI: That's neuroscientist Jim Hudspeth. You can watch his full talk at ted.com.
KELLY: And you can hear the rest of that TED Radio Hour episode, Sound And Silence, wherever you get your podcasts.
(SOUNDBITE OF RAC'S "CUTSCENE 1") Transcript provided by NPR, Copyright NPR.
