09/09/2016

Breakthrough: Hearing a Whole New World

17:07 minutes

Welcome to the first installment of “Breakthrough: Portraits of Women in Science,” a new series that follows the innovative research of women scientists. In this episode, Rene Gifford, director of the Cochlear Implant Research Laboratory at Vanderbilt University, discusses how she and an interdisciplinary team developed methods to improve cochlear implants by fine-tuning how implanted electrodes stimulate nerve cells. Gifford’s colleague, audiologist Allyson Sisler-Dinwiddie, became a test subject after an accident plunged her into complete silence.

Documentary video producer Emily Driscoll joins Ira to share Sisler-Dinwiddie’s story. And Gifford describes how turning off electrodes in an implant could, surprisingly, improve the wearer’s hearing. They’ll also discuss other research that’s exploring ways to help people who wear implants enjoy music and experience directional hearing. And they’ll examine how more people may benefit from these implants than the FDA currently considers suitable.

Segment Guests

Emily Driscoll

Emily Driscoll is a science documentary producer in New York, New York. Her production company is BonSci Films.

Rene Gifford

Rene Gifford is an associate professor of hearing and speech sciences at the Vanderbilt University Medical Center in Nashville, Tennessee.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow.

[CHATTER]

That’s an approximation of what you might hear if you were trying to listen to a conversation while relying on a cochlear implant to hear. Could you make out the spoken words above all that background noise? Yeah, me neither. Cochlear implants are an increasingly useful tool for people who have had hearing loss so complete that they can’t be helped by hearing aids. But they do have some drawbacks, like electrical interference that can make it harder to pick out words. And they have trouble filtering background noise from useful conversations, just like that little sample we heard.

That brings us to our story. Picture that you’re studying to be an audiologist and, ironically, relying on an implant to connect you to the world. That was the situation in which Vanderbilt audiologist Ally Sisler-Dinwiddie found herself after a car accident took away her hearing midway through graduate school. Emily Driscoll, a science documentary producer here in New York, tells Allie’s story and premieres our new video series about scientists who have overcome challenges to do their work.

Welcome back, Emily. Good to see you.

EMILY DRISCOLL: Thanks. Thank you.

IRA FLATOW: Also here to talk more about the research that’s making implants more useful to people like Ally is Rene Gifford. Dr. Gifford is an associate professor of hearing and speech sciences at Vanderbilt University Medical Center in Nashville, Tennessee, and she’s joining us on the phone. Welcome to Science Friday.

RENE GIFFORD: Thank you.

IRA FLATOW: Emily, first, our congratulations on the start of this. This is a great new series. Tell us about– Breakthrough it’s called, right?

EMILY DRISCOLL: Yeah, it’s really exciting. It’s been over a year in the works. And Luke Groskin and I produced it. It’s called Breakthrough: Portraits of Women in Science, and it’s six films that follow scientists across STEM fields. And the films reveal the personal stories of these scientists, as well as the cutting edge and innovative research that they’re working on.

And we really want to show what is it like to be a scientist. What are the difficulties and the challenges, but then also the excitements and rewards of what it’s like to be a scientist. And we follow different kinds of researchers, like one whose work takes her to very harsh conditions in the Arctic. We also have a portrait of one woman who studies sneezes and how snot breaks up in sneezes to understand the fluid dynamics of disease transitions– excuse me, disease transmission.

And the next episode takes us to ISRO, which is the Indian version of NASA.

IRA FLATOW: Wow. Let’s talk about your first video. The first video tells us the story of an audiologist who persevered through hearing loss.

EMILY DRISCOLL: Yes, the first episode premieres today, and it’s called “A Resounding Remedy.” And it follows audiologists Ally Sisler-Dinwiddie and Rene Gifford at Vanderbilt. And they have a really unique situation because Ally was studying hearing sciences, and here she was in her graduate work when she got into a car accident, and it plunged her world into silence.

So she was thinking, how do I help people hear when I myself can’t even hear? So she ended up getting a cochlear implant, which restored some of her hearing, and she was able to work again. But then she was in a very unique situation in which her colleague Rene Gifford became basically her doctor, because Rene was working with this interdisciplinary team on this way to improve cochlear implants. And Ally was one of the first test subjects.

IRA FLATOW: We have actually have a little bit of a clip from the video. And this is where Ally describes how implants changed her access to the world.

ALLY SISLER-DINWIDDIE: When I got my first cochlear implant, I went from nothing to a world that’s so far beyond what my hearing aids were ever able to provide. And I had no idea how much I missed growing up. No idea.

IRA FLATOW: Dr. Gifford, Ally already had hearing aids. How is a cochlear implant different than hearing aid?

RENE GIFFORD: That’s a great question. So cochlear implants are really designed for people who have more severe hearing losses. So those who, despite using appropriately fitted hearing aids, are really struggling for communication in everyday life.

IRA FLATOW: This is where your story and Dr. Sisler-Dinwiddie’s intersect. You’re working on how disabling parts of the implant– ironically, if you disable part of it, you can actually improve the hearing of people?

RENE GIFFORD: That’s absolutely right. It’s almost sort of a scientific less is more. So we’re basically taking certain electrodes and deactivating them in an effort to try to reduce some of the electrical interference that we see with cochlear implants.

IRA FLATOW: So how do you know which electrodes might need to be turned off?

RENE GIFFORD: So what we’re using is we’re using imaging to help guide us. So we use pre-operative as well as postoperative CT images, and we basically will build a 3D reconstruction of their internal auditory system. And by having that pre-operative CT scan, we’re able to have a nice artifact-free image.

And then we can sort of superimpose the post-operative CT scan when the electrode array is in place, along with, of course, the metallic artifact that we see because of the implanted electrode array. And then we can actually measure discrete distances between each of those implanted electrodes and the actual auditory neurons that we’re trying to stimulate. It’s basically just simple distances.

IRA FLATOW: Emily, why did you choose this story? What made her so her story so compelling?

EMILY DRISCOLL: The innovative research that they’re working on, and the fact that hearing is so complex to begin with. And look, we’re putting an electrode array down into our cochlea and stimulating nerve cells. And the turning off some of those electrodes was fascinating.

But then I don’t know if you’ve ever seen an activation or someone getting their cochlear implants turned on online, but it’s such an emotional, powerful thing to see people hearing again, some of them hearing for the first time. And we were able to see this. We were able to be there for an activation. So that’s one of the most powerful parts in the film. And then Ally’s story as well.

IRA FLATOW: Rene, exciting to you, too?

RENE GIFFORD: Oh, so exciting. It’s one of the best things I get to do. It’s truly a pleasure.

IRA FLATOW: And in the video, we see when she gets her cochlear implants activated for the first time and crying when she hears her parents’ voices.

EMILY DRISCOLL: Yeah, that was one of the most special parts. When she was talking to Rene, she didn’t know have much of a reaction. But then Rene said, turn around and talk to your parents, and then she remembered. She said, you sound the same. She remembered how they sounded.

IRA FLATOW: Wow. It gives you a great feeling, Rene, to be involved in this research, I’m sure.

RENE GIFFORD: Oh, absolutely.

IRA FLATOW: How does hearing loss or impairment usually happen, Dr. Gifford? Tell us, where does it happen in our ear? In most cases, what’s going on?

RENE GIFFORD: Yeah, so, great question. From the adult perspective, the vast majority of hearing losses are what we would consider unknown. We probably believe that a majority of them are due to genetic reasons. But because we don’t understand all of the underlying genetic mechanisms that potentially contribute to hearing loss, we don’t fully understand exactly what’s causing this. Of course, environmental factors including noise exposure, toxins in our environment, taking, for example, medications that may be toxic to the auditory system. These are all things also that can cause hearing loss.

Typically, what we do see, however, is that it’s the actual structures within the cochlea itself. So the cochlea is a snail-shaped organ that actually lives inside the temporal bone. So it’s the side bone– the side of our head, and it’s the strongest bone in the body.

And within that cochlea, there are these very delicate– they’re called hair cells. And over time, with damage of whatever type of damage it might be, those hair cells will ultimately become dysfunctional, and then ultimately die. And those hair cells are the primary means by which that incoming sound that hits our ear, it hits our eardrum, are transduced to the auditory nerve. So when those cells start to die off, there’s really absolutely no way to completely transmit that sound to the auditory brain.

IRA FLATOW: Well, Emily, I want to thank you for the new video. It’s a great video. You can check it out in our Breakthrough series on our website at sciencefriday.com/hearing. I’m going to let you go because I know you’re about to fly to India for our next video. Can you give us a hint, a little bit of a hint?

EMILY DRISCOLL: Sure, it’s really exciting. We’re going to ISRO, the Indian space agency, and we’re going to see what it’s like to work on their first interplanetary mission.

IRA FLATOW: Wow. So have a good trip, safe trip!

EMILY DRISCOLL: Thank you.

IRA FLATOW: Emily Driscoll, science documentary producer based here in New York. Dr. Gifford, let’s talk a little bit more about your research and the progress of cochlear implants. How do you know when you should have one?

RENE GIFFORD: So it’s not a cut and dry answer for everyone. We tend to say once someone is no longer able to, say, talk on the phone without visual cues, whether it be texting or a caption type of telephone, or when someone is completely reliant on visual cues for communication, that’s a really good indication that someone has progressed to the point where they might be a candidate for an implant.

IRA FLATOW: And what will it do that the hearing aid can’t do? I mean, is it mostly for people who have the hair cell loss that most people are going to get eligible for that?

RENE GIFFORD: Absolutely. So I explain to my own patients that we could provide them with the world’s most expensive hearing aid, the very best technology, but it’s almost as if trying to play music through a broken speaker. We can amplify the sound and we can shape the sound, but the ear is not capable of transducing that sound to the auditory nerve, and then ultimately up to the auditory cortex.

IRA FLATOW: I know one of your big projects is bilateral hearing, how an implant could work with a small amount of retained hearing ability. How could these two work together?

RENE GIFFORD: So I do focus primarily on– it’s the combination of electric and acoustic hearing. So the electric hearing through the cochlear implant itself, which is just actually stimulation of the auditory nerve through those electrical pulses. As combined with the natural acoustic hearing of our own ear, which is basically just referring to the sound pressure waves hitting the external ear and eardrum and propagating through the auditory system.

And basically what happens is when you can combine those two very distinctly different modalities of hearing, they can combine to provide the synergistic tremendous improvement in not only sound quality, but also in speech understanding, in quiet as well as in noise.

IRA FLATOW: So we actually can compare. We have a little audio demonstration here to compare how that might sound. Let’s first hear what it might sound like to hear with a cochlear implant with background noise.

[CHAOTIC CHATTER]

Wow, you can hardly hear the conversation going on. There is a conversation going on, and I want to show you that. We also have a simulation of preserved normal hearing, at least in registers below 500 hertz.

[MUFFLED CHATTER]

So Dr. Gifford, what’s the difference? How is it working better there?

RENE GIFFORD: So you probably immediately could tell that it just sounded more natural. You could actually kind of almost extract out the talker’s voice from the presence of that background noise. So by adding even a very small amount of acoustic hearing, and I’m talking about acoustic hearing that if presented in isolation would give you really essentially no intelligibility whatsoever. But when you combine that with that electric signal, you’re able to really essentially extract out the portions of that talker’s voice that makes it sound like natural speech and allows us to really, truly extract that speech in the presence of the background noise.

IRA FLATOW: But if you have some sort of residual hearing left over, isn’t that kind of a risky, then, to go through surgery to have a cochlear implant if you can still hear something?

RENE GIFFORD: Yeah, I mean, it certainly could be. But we’re in a much different place today than we were even just five, 10 years ago. So with advances in surgical techniques and advances in more atraumatic electrode arrays, we’re actually seeing tremendous amounts of hearing preservation, even in the implanted ear.

And so what I mean by that is that if an individual has relatively decent low frequency hearing or hearing in the low pitches, even by surgically implanting an electrode array in that ear, it’s very possible to preserve that low frequency hearing. And then you can combine that electric and acoustic hearing not only across ears, but within the implanted ear as well.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from PRI, and Public Radio International. Talking with Dr. Rene Gifford of Vanderbilt.

The big question, the money question. Everybody asks about money. So there are cochlear implants. Are they affordable? Will Medicare pay for them? Medicaid? How can you get one?

RENE GIFFORD: Great question. So Medicare does currently provide coverage for cochlear implantation. Of course, the patient does need to meet the criteria, which currently is up to 40% correct on sentences presented in an auditory-only condition with hearing aids.

Medicaid’s a little trickier. As you know, Medicaid is actually on a state-by-state basis. For children now, all states will provide cochlear implantation for state Medicaid. But for adults, so once someone reaches the age of 21, there are some states that just will not provide cochlear implantation coverage, such as the state in which I live, Tennessee.

IRA FLATOW: Is that right?

RENE GIFFORD: Absolutely, yeah.

IRA FLATOW: Does Obamacare or corporate care, health insurance cover it?

RENE GIFFORD: Most generally. However, each of those policies under the Affordable Care Act are different somewhat, and some of them actually have some exclusions. So, of course, based on affordability, you might choose more of a discount policy, for example. And there are sometimes exclusions that would exclude cochlear implantation entirely. So you have to be careful.

IRA FLATOW: You feel that it’s important to get young kids to have these things, have the implant.

RENE GIFFORD: Absolutely, and the earlier, the better. I mean, there are just mounds of data showing that the earlier, even younger than one year of age, you can yield very normal speech and language development. With, of course, the appropriate speech and language intervention.

IRA FLATOW: What makes hearing such a crucial field of research in your mind and why you’re involved in it?

RENE GIFFORD: From day one of my life, I remember that hearing was an issue. So I was raised by my grandparents, and my grandfather was a World War II veteran. And he actually was a purple heart recipient.

He had been shot down– he was a paratrooper, and he had been shot down. And from that point forward, he had a very severe to profound hearing loss, but it was really only in the higher pitches. So he was one of these individuals who tried hearing aids and just really never derived any benefit. And so I knew from the time I was in diapers that communication was vital, and you had to look at someone, and you had to talk.

And so from my entire life, hearing and communication has been so tremendously important.

IRA FLATOW: I’m going to give you the blank check question. If you had a blank check to advance technology or come up with an improvement, what would you like to have in cochlear ear implants?

RENE GIFFORD: Well, I’ll tell you. Right now, the current technology is pretty remarkable, because what really is happening is the brain is taking this very rather crude signal, and is making it and changing it in ways that we never, ever thought possible. So if I had a blank check, I would not necessarily apply changes in technology to today. But I would actually want to make this technology available to every person around the world who actually needed it, because that really is the issue. There are places in the world where this technology is absolutely inaccessible due to funding purposes.

IRA FLATOW: That sounds like a good mission, Dr. Gifford. Thank you very much for sharing it with us.

RENE GIFFORD: Thank you.

IRA FLATOW: Rene Gifford, associate professor of hearing and speech science at Vanderbilt University Medical Center in Nashville, Tennessee.

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