“Hearing music with only one ear engages only half of the brain. Hearing Clair de lune with two ears was like the difference between a live and a dead body: the form was the same, but the experience was oh so different.”
On January 24, 2008, I sat in my audiologist’s office waiting to have my new right ear turned on. For the first time in 30 years, I was about to hear in stereo again.
I’d dealt with hearing loss all my life, because my mother got rubella when she was pregnant with me. I had used hearing aids since the age of three, but gave up on the right ear in the 1980s after it gradually died. In 2001, the left ear died too. During a business trip in Reno, things began to sound fuzzy. After four hours I canceled my meetings and stumbled back to San Francisco, shocked, dizzy, and totally deaf.
The cause of what happened that day in 2001 is unknown, but the general reason for my deafness was clear. The inner ear, called the cochlea, is a pea-sized, snail-shaped organ lined with thousands of tiny hair cells that vibrate when sound hits them. The hairs trigger nerve endings, which send information to the brain. Most cases of deafness are caused by damage to the hair cells precipitated by things such as noise or viral infections. Before 2001 I had enough hair cells remaining in the left ear to benefit from the amplified sound of a hearing aid. Then, for some reason, they too were destroyed. My auditory nerves remained intact, but there was nothing to trigger them.
The nerves could be triggered, though, by a device called a cochlear implant. In September 2001, a surgeon at Stanford Hospital drilled an inch and a half into my head and threaded 16 tiny electrodes into my left ear’s cochlea. The electrodes were controlled by a computer chip embedded in the surface of my skull underneath the scalp. After a few weeks of healing, I got an external computer that sent it data. It sat on my ear, looking like a hearing aid, and radioed a megabit of data per second to the chip in my head.
I had only one ear done in 2001 because it was the standard practice at the time. It had worked out well: I was able to use telephones, listen to the radio, and converse at parties. But with only one ear, I still had significant limitations. I couldn’t tell where my students’ voices were coming from. A sound coming from a person’s right side will reach the left ear a few hundredths of a second later. The brain has neurons specifically designed to compare the two ears and detect time differences, giving rise to the sensation of it’s over there.
With one ear, I had to rubberneck until I found who was speaking. It took me a second or two to do that, hence I lost the entire first sentence and apologetically had to ask the student to start over. In 2006, after another frustrating semester, I quit teaching. I went to my surgeon and said, “I think it’s time to go bilateral.”
At first my insurer, Aetna, wouldn’t cover getting a second ear. Of about 100,000 implant users worldwide, about 3,000 of them had gone bilateral. (One implant costs about $50,000; getting two simultaneously costs somewhat less than twice as much, since there is only one surgery.) Drawing on that population of 3,000, many studies had come out since 2001 confirming the benefits of having two functioning ears. In late 2007 Aetna changed its policy, joining a growing list of insurers that cover bilateral implants.
On December 17, I had my right ear implanted. The surgery was amazingly easy—much easier than the first time. It took the surgeon only 43 minutes. I went in at 8 a.m. and was back home by 2 p.m. Instead of being groggy for three days, as I was with the first ear, I stuffed myself with omelettes that night and went to the supermarket two days later.
Five weeks later, I was in my audiologist’s office to have my new ear turned on by getting the external processor. It had taken me months to learn to hear speech again with my first ear, so I wasn’t expecting perfect clarity from the start. The right ear had gone unstimulated for much longer than the left, so it had more catching up to do.
It is, as fur as he knuzz, th’ only wy of coming downstrrrs, but sumtimes he fils that there rilly is another wy, if only hih could stop bumping for a mument and think of it. And then he fls that purhaps there iznt. Unyhw, here hih is at the bottom, and ready to be intriduced to yu. Winnie-the-Pooh.
The “missing” vowels threw me off; I could follow the voice only by reading along with the text. The implant was in fact giving me the vowels. I just couldn’t hear them yet, because I hadn’t learned to recognize the way they were being picked up by the nerves. That would come with time, practice, and tweaks of the software. I would have to go back to the audiologist several times over the next six months to get the software to fit just right to the ear.
But the ear was already pulling its weight. The next day I went to a café with two friends. Even though my new ear couldn’t have understood them on its own, it backed up the other ear. An “s” heard by my left ear was matched by a sensation of crispness in the right, making it more definitively an “s.” It made it much easier for me to hear them amidst the yammering of the patrons and the yowling of the cappuccino machine.
Here’s an analogy. Say that hearing’s like walking a narrow beam across a river. It helps to have a rope on one side to hold onto—that’s like having one ear. But having a rope on both sides makes the trek firmer and more solid; a sway in one direction can be corrected by pushing on the other. It let me relax and enjoy the conversation instead of having to struggle for each phoneme.
And then I tried music. I started with Debussy’s Clair de lune, a slow, reflective piece played by an oboe and a harp. I could feel the new ear feeding me its version of the soundstream. It didn’t sound as limpid and clear as the left, but it was giving me music, mirroring the left. Mirroring? Actually, no, I realized. The headphones were shifting the sound intensities back and forth between them, playing off of each other.
Stereo.
And I was caught up in it: following the contours of the piece, its wholeness, its probing of the emotional resonances of sound; a moonlit glade with the stars wheeling overhead.
“It sounds lovely,” I breathed.
Wow.
It held my attention the way a good story does. I listened to it three more times, once with only the right, once only with the left, then once with both again. Disassembling and reassembling the piece.
I realized that listening to music with one ear is essentially pointless. Music reaches into you and works on your brain. To do that, it needs to work on all of the brain. Hearing music with only one ear engages only half of the brain. Hearing Clair de lune with two ears was like the difference between a live and a dead body: the form was the same, but the experience was oh so different.
And then, a few days later, I was walking up one of San Francisco’s many hills when I heard the shouting and laughing of children behind me. I couldn’t see them. I slowly pivoted on my heels. The racket sounded different at every point of the compass. I could feel it increasing in one ear at the same time that it diminished in the other ear. There came a point, in one particular direction, when both ears came into synchrony. My body said: It’s over there.
I walked on, and a few steps later a school playground came into view, two blocks away, full of children.
I haven’t returned to the classroom yet. It’s only been a few weeks. But having two ears has opened up new dimensions for me. Just as the studies have shown, it’s easier for me to hear people talking in noisy environments and lets me tell where sounds are coming from. And music has gone from being interesting data to being alive. It’s like cupping water with two hands instead of one. You can do it with one. But you get much, much more with two. My brain, like everyone else’s, was designed to work with two ears. Being bilateral gives me a fresh chance, after 30 years, to hear the world whole and full.
Michael Chorost, Ph.D., is a freelance science writer based in San Francisco. His book about getting his first cochlear implant, Rebuilt: How Becoming Part Computer Made Me More Human, came out in 2005. He covers medical devices for several magazines and frequently gives talks on emerging technologies.
April 30, 2008
http://www.burrillreport.com/article-living_in_stereo.html