I Can Hear You Whisper (22 page)

“Do you really need all that spectral information to extract something intelligible?” Poeppel asks.

The answer is no. Some of the spectral information, the combination of frequencies that makes up each sound, turned out to be icing on the acoustic cake. In the early 1980s, several researchers, notably Robert Remez at Barnard University and Philip Rubin of Haskins Laboratories, created spectrograms of spoken sentences, got rid of the fundamental frequency (the band at 100 Hz in “ibex”), extracted the formants (the remaining bands), and replaced them with sine waves. With sine waves standing in for formants stacked up at the appropriate frequencies, the sentence is intelligible. If you practice, that is. Poeppel plays me some samples from the Haskins Laboratories website. At first, I just hear high-pitched whistles like the sounds Jodie Foster interpreted as alien communication in
Contact
. But after Poeppel plays the natural sentence and then replays the sine-wave sentence, I hear it: “The steady drip is worse than the drenching rain.” Do this for twenty minutes, Poeppel tells me, and you'll get really good at it.

At the House Research Institute in Los Angeles, an auditory neuroscientist named
Bob Shannon and his colleagues took a different approach. They manipulated sentences not by minimizing the spectral information but by degrading it. When the ear groups similar frequencies into critical bands, or channels, along the basilar membrane, there are typically about thirty in a healthy ear. In an influential experiment, Shannon and his team took a set of sentences and reduced the number of channels used to convey them, as if thirty radio stations were trying to broadcast from just a few spots on the dial. Condensed into one big channel, the sentences were basically unintelligible. With two channels, there's minimal information, but still not enough to understand much. With three channels, the sentences coalesce into words. “The difference between two and three is huge,” says Poeppel. “At four, you're almost at ceiling.” In other words, when asked to repeat what you heard, you would get nearly every sentence even without the remaining twenty-six channels of information about sound you normally use.

What if you leave the spectral composition of sentences alone and change only the timing, what scientists call the temporal information, instead? One of Poeppel's frequent collaborators, Oded Ghitza, a former Bell Labs scientist and now a biomedical engineer at Boston University, worked with auditory neuroscientist Steven Greenberg to play with the rate of sentences. Consistently across languages, normal conversation runs at about four to six hertz.
Ghitza and Greenberg compressed sentences so that what originally took four seconds to speak now took two. Listeners could still understand them. But when they compressed the sentence again, by a factor of three, it got much harder. Poeppel plays me an example and it sounds like a garbled mouthful: badazump.

But Ghitza and Greenberg weren't done. “They take the compressed waveform,” says Poeppel, “which sounds for shit, and they just slash it into little slices and they add silence in between.” Now it sounds like “bit . . . tut . . . but . . . tit.” Poeppel explains what I'm hearing: “The acoustic signal is very small and not informative, totally smeared and gross, but you've added a little bit of empty time in there. You've squished everything and now you insert little silent intervals.” Then Ghitza and Greenberg measured how many mistakes listeners made when trying to repeat the sentences. With the speech totally compressed, the error rate was 50 percent. As they increased the intervals of silence, the error rate went down by 30 percent. But then it got worse again. “That's weird, right?” says Poeppel. “There's this moment where you do better, even though the acoustic signal is still totally crappy.” That sweet spot came with silent gaps of eighty milliseconds. What Ghitza and Greenberg concluded was that from a brain's-eye view, a listener needs two things. The first is what they term an “acoustic glimpse”—the pitch, loudness, and timbre carried on the sound wave that tell the system to listen in. Then the brain needs what they call a “cortical glimpse,” which is simply time—enough time to decode the information that has just arrived.

Poeppel has one last hall-of-mirrors trick he wants to show me. It's one he often uses in presentations. First, he sets a black arrow moving from left to right across his computer screen. “We have this very powerful intuition that time flows like an arrow in this particular direction,” he says. “That of course is true. It's the second law of thermodynamics. But at a local level, that turns out not to be quite right.” Now he clicks on a recording of a sample sentence. It sounds like high-pitched chirping. The second sentence, too, is high-pitched and choppy, but now I can make it out: “Ants carry the seeds so better be sure that there are no anthills nearby.” I can also understand the third, which is similarly distorted: “We've all been rich and spoiled long enough to hate the machine age.” (I notice there's never just a sentence about making spaghetti for dinner.)

“One you didn't get, the others you did,” says Poeppel. “Why are those of any interest?”

He pauses before delivering the punch line.

“They're all played backward.”

“Even the ones we can hear?” I ask, amazed. I knew about the Beatles' famous backmasking on “Revolution 9,” but it didn't sound like this.

“That is the rub. Here's a spectrogram of a regular forward sentence.” He shows me a now familiar image of splotchy bands of energy. “Now you take a regular forward sentence and you slice it up into little chunks again. But now you flip them backward.”

He makes this sound simple, and for auditory engineers it is. Once they have a representation of a sound signal on a computer, they can manipulate it every which way. For a layperson like me, it takes a while to get my head around the idea.

“Flip the whole sentence?” I finally ask.

“No, you flip the slices.”

If you flipped the whole sentence, he explains, it would sound syllabic but unintelligible. Each small slice is another story.

“Do the backward slices equate to a word?”

“That's the question. What's the size?”

After playing around with the size of the slices, the researchers who dreamed this up found that the fundamental size that had to go forward was the length of a syllable, or about one hundred fifty to two hundred milliseconds. “When you go to the size of a syllable, you're not allowed to play this game,” says Poeppel. “That's one of the reasons the syllable is very foundational to perceptual parsing.”

Taken together, what all these acoustic manipulations have demonstrated is that the sounds we hear have to be good enough. “‘Good enough' can mean a reasonable amount of spectral information and a clear amount of temporal information,” says Poeppel. “You need the temporal information to segment into some kind of unit, and you need the spectral information to begin to initiate the process of looking stuff up. But that's all: If it's good enough, it gets you there.” And it starts the cascade of responses rippling through your brain.

I
n April 2006, a group of two- and three-year-olds clustered around our dining room table, propped on their knees in their chairs and leaning forward, Spider-Man party hats askew, so as to get closer to the cake.

“Happy birthday to you, happy birthday to you . . .”

Alex had turned three. The deadline that Simon Parisier had set had arrived. We had gotten the cochlear implant in under the wire and already it was making a difference.

Nonetheless, the day was bittersweet.

The boys and girls celebrating with us mostly lived nearby in Brooklyn. As one- and two-year-olds, they had attended the same local child care center as Alex. They were a reminder of how much had changed in our lives.

I tried not to focus on the children's chatter as they ate their cake, but it was inescapable. They were a talkative group.

“For my birthday, I got Spider-Man, too!” said one little boy. “He makes webs.”

“I'm going shopping with my mommy after this,” said one precocious girl.

“I love chocolate cake!” cried another.

Alex had blown out his candles with enthusiasm and climbed on the living room furniture with some of the boys. When you're two or three, giggling is a universal language. But that was largely the extent of his communication with these children. When he did talk, I was usually the only one who understood him.

In the coming year, I didn't know if Alex would see any of these kids at all. Up to this point, in order to preserve neighborhood friendships and maintain some normalcy, we had kept him enrolled in the familiar child care center near home—Jake and Matthew and some of their closest friends had been there, too. We'd been dropping Alex off there for the afternoons after his morning sessions at Clarke. As a three-year-old, however, Alex would be in Clarke's preschool program all day and would leave the neighborhood behind. To make that work, I was even going to let him take the school bus, an idea that had appalled me when my friend Karen first mentioned it back at the very beginning of this journey. All my certainties about what was possible for a child Alex's age had been knocked upside down.

Now I was (pretty) sure this was the right thing to do. At Clarke, Alex would have teachers of the deaf in the classroom who could do the explicit language teaching he needed, his speech therapy would be a routine part of his day, there would be audiologists on hand, and everyone in the building knew how to manage his equipment. We were fortunate to have such a school available to us.

But the decision marked the first complete diversion from the life we had imagined for Alex, from the life his brothers were leading, a life of growing up in our brownstone Brooklyn neighborhood, where I rarely got to the grocery store without seeing an acquaintance and where the boys rarely went to the playground without meeting a friend, where I could walk them to school every morning and wave to the same set of crossing guards for years. Instead, Alex would be across the East River at the other end of the city from me, with children I hardly knew. Although I would visit occasionally, my sense of his days would be mostly limited to the weekly reports from his teachers and therapists and to the yellow bus that picked him up at seven each morning before his brothers were even awake and dropped him off in the afternoons. Alex was zigging while everyone else was zagging. For a year? For two? Forever? All we could do was work and watch and wait.

 • • • 

“Cat,” said the speech therapist. Alex moved a toy car a few inches along the table to show that he heard a short vowel sound.

“Cake.” Alex moved the car three times farther for a long vowel.

It was June. Six months into having a cochlear implant, Alex was being evaluated again. The therapist recorded some of what he said, mostly simple phrases like “going to work” and “it broken,” but also an impressive five-word string—“Let me have yellow hat”—while playing with Mr. Potato Head, who featured regularly in evaluations. Still, omissions, distortions, and substitutions like “boo” for “blue” and “wowuh” for “flower” littered his speech, leaving him with the articulation of a child a year younger.

 • • • 

“Mama, want mik, pees,” Alex called to me in August as he ran through the kitchen with his friend Nina.

“Of course, sweetheart, I'll get you some milk,” I answered and got up from my stool to go to the refrigerator.

“Lydia!” Across from me, my friend Amy, Nina's mother, who had known Alex all his life, was looking at me with surprise.

“I understood him!” she said. “That's the first time I've ever understood him.” Only now could she admit to me that she never had before.

 • • • 

After a doctor's appointment one morning that fall, I delivered Alex to Clarke later than usual.

“Alex, I've been looking all over for you!” said his teacher when we reached the classroom. She pretended to look behind the door.

“Here I am!” he announced. “I was looking for you, too!” Then he pretended to look under the table.

To my amazement, my sweet but silent baby was turning into a funny boy, quick with a laugh and eager to play along with a joke.

 • • • 

In December, I sat once again at the observation window at Clarke, watching Alex and his classmates play. He had arranged a group of blocks to form a boat and was sitting amidships. When some of his classmates climbed in with him, he handed over a long foam block.

“Row the boat!” he commanded.

Then he picked up another block and pretended it was a fishing rod.

“I have a big fish! Help me pull!”

The children laughed and began to row and pull.

 • • • 

Each sign of progress was thrilling but brought a new dilemma. Almost as soon as we decided to put Alex at Clarke full-time, we had to consider what to do the following year, when he would be four. The goal of a specialized school like Clarke is to prepare children for the mainstream, not to hang on to them longer than necessary. How long was necessary? Would I know by watching through the window? Educating Alex, I was learning, was going to be a moving target. Every year, we would have to reassess and rethink.

Jake and Matthew were in third grade and kindergarten respectively at Berkeley Carroll, a wonderful school five blocks from our home. If Alex was going to join them there the following year, the application would be due in December, long before it seemed we could know if he'd be ready.

I asked the teachers at Clarke to fill out the necessary recommendation forms anyway. When I got them back, I was surprised to see how little indicated that Alex was different from any other child. Of course, his classroom teacher had noted he was behind on every aspect of speech and language. But on a long list of social and behavioral skills such as attention span, ability to focus, curiosity, enthusiasm for new challenges, interaction with peers and adults, Alex looked like a very skillful little boy. Many categories were marked as an “area of strength.” Suddenly, I was seeing my child afresh. I had been so fixated on nurturing the seedlings of Alex's language that sometimes all I saw was the dirt, the weeds, and the tender but fragile sprouts of words and sentences. I needed to stand up and look at the whole garden that was my child. Focused on what I feared he couldn't do, I didn't always take time to savor what he could.

Encouraged, I told myself we were just keeping our options open by applying to a mainstream school. On the day the application was due, my truer emotions spilled out as I walked up the street to hand-deliver the forms. My heart started thumping and my palms got sweaty. Half a block from the school, I stopped and stood on the corner for a few minutes. Simultaneously thrilled and terrified, weighed down and released, I wanted to protect Alex and I wanted to push him. I wanted him in a safe haven and I wanted him in the wider world. I looked at the big white envelope in my hands. Once I turned it in, at least, part of the decision would be in someone else's hands.

 • • • 

While we waited to hear from Berkeley Carroll, the anniversary of the activation of Alex's implant arrived in January, a few months before his fourth birthday. It was time to measure his progress. We went through the now familiar barrage of tests: flip charts of pictures to check his vocabulary (“point to the horse”), games in which Alex had to follow instructions (“put the purple arms on Mr. Potato Head”), exercises in which he had to repeat sentences or describe pictures. The speech pathologist would assess his understanding, his intelligibility, his general language development.

To avoid prolonging the suspense, the therapist who did the testing calculated his scores for me before we left the office and scribbled them on a yellow Post-it note. First, she wrote the raw scores, which didn't mean anything to me. Underneath, she put the percentiles: where Alex fell compared to his same-age peers. These were the scores that had been so stubbornly dismal the year before: eighth percentile for receptive language (what he could understand) and sixth percentile for expressive language (what he could say).

Now, after one year of using the cochlear implant, the change was almost unbelievable. His expressive language had risen to the sixty-third percentile and his receptive language to the eigthty-eighth percentile. He was actually above age level on some measures. And that was compared to hearing children.

I stared at the Post-it note and then at the therapist.

“Oh my god!” was all I could say. I picked Alex up and hugged him tight.

“You did it,” I said.

From the evaluation, we went straight to Clarke so Alex could go back to school. The director's office was next door to his classroom. I knocked on the door frame and Teresa Boemio looked up from her desk.

“How did it go?” she asked as soon as she saw me. She knew where we'd been.

“Pretty well.”

I handed over the Post-it note.

“Wow!” she cried. “WOW!”

She pulled his teacher out of the classroom and showed her the numbers. Then they grabbed his speech therapist. All of us started hugging and whooping as if our team had just won the Super Bowl.

“I don't know if I've ever seen a kid do this well this fast,” said Teresa.

There was no way to know exactly how Alex was hearing the world, but the trajectory of his language development said that whatever he was hearing was good enough. It had made him a success story. Unquestionably, he had a lot going for him: usable residual hearing, teachers and therapists who knew how to help him, parents who talked and read to him a lot, even two older brothers who discussed the finer details of superheroes and how to play hide-and-seek with him day in and day out. But hearing aids alone had not been enough for Alex. The transformation came with the cochlear implant. Like the difference between candles and fluorescents, Alex's residual hearing registered the world dimly and imprecisely except within a few small circles of light, while his cochlear implant lit everything up brightly if unnaturally. Once he had seen everything clearly, he could make better use of the warmth and ambience he got from his natural hearing, and he knew what lay in the shadows. Language followed.

 • • • 

That night, after the family celebrated, Alex sat on his bed and we talked some more about the day.

“You did so well today,” I said and did the family dance of success that Mark had invented. It involved circling my fists and hips and chanting, “Go, Alex. Go, Alex.”

He laughed.

“So no more processor?” he asked, referring to the external part of his cochlear implant.

I stopped dancing and stared at him.

Had we really never explained that he would always be deaf? It had never occurred to me that he might think otherwise. Every night, when he took off his aid and processor, he went back to being almost entirely unable to hear. After all, the internal implant only worked when the external implant was in place. To tell him I loved him when I tucked him in, I had to get up close to his left ear and shout.

He and we had managed a major achievement, but already we were entering a new phase. It wasn't just education that would be a moving target. His sense of self, his emotions, his identity would shift and evolve. I had had nearly two years to come to terms with Alex's hearing by then. Now it would be his turn. We would have to use his newly acquired language to help him understand. The pride and acceptance of Deaf culture suddenly took on new significance. I found myself dearly hoping that Alex would follow their lead and come to view his deafness simply as a difference. My next job would be to help him do that.

At least his success made it easier to decide to send him to Berkeley Carroll as a four-year-old the next September. I tried not to think about what lay ahead, even though I could guess. Jake was entering fourth grade and reading chapter books, writing short essays, and working with fractions. Matthew was going into first grade and reading as well. Would the sound Alex was getting allow him to accomplish all of that, too? Would he be able to build on the language he had and keep pace?

As I readied the boys for the first day on which they would all attend the same school, however, I thought not about the future but about the effort that had gone into getting us this far. I helped Alex strap on his new pint-size blue backpack, with his name stitched in white, then took his hand to maneuver our stoop while Jake and Matthew waited on the sidewalk. Watching the three of them race to the corner together, our ordinary walk to school suddenly seemed extraordinary.