THE  BRAIN'S  WAY  OF  HEALING  by  Dr. Norman  Doidge


The Auditory Zoom

Tomatis kept making discoveries at a feverish pace. He noticed that when subjects listened with the Electronic Ear, filtered so they heard like Caruso, they pronounced the letter r with a distinctly Neapolitan accent. Knowing that Caruso was from Naples gave Tomatis an idea. Perhaps accents, too, are a function of the frequencies people hear. Testing, he soon found that the French, for instance, hear in two ranges, 100 to 300 Hz and 1,000 to 2,000 Hz. Speakers of British English hear in one higher range, from 2,000 to 12,000 Hz, which makes it hard for French people to learn English in England. But North American English involves frequencies from 800 to 3,000, a range closer to the French ear, making it easier for the French to learn.

Soon Tomatis was able to help people learn second languages by setting up the filters that reflected those of a native speaker. These "different ears," he argued, were probably based on different "acoustic geographies." Whether a speaker is raised in a forest, on an open plain, on mountains, or by the sea has a major impact on the sounds he hears, because certain frequencies are muffled or amplified by different environments. When he set the Electronic Ear's filters to "British ear" and put it on French children who were studying British English, their English improved, and for some reason, their grades in other subjects did too. So Tomatis increasingly turned his attention to the relationship between these "different ears" and language, learning, and severe learning problems.

Arguably his most important discovery was that the ear is not a passive organ but has the equivalent of a zoom lens that allows it to focus on particular noises and filter others out. He called it the auditory zoom. When people first walk into a party, they hear a jumble of noises, until they zoom in on particular conversations, each occurring at slightly different sound frequencies. Once a person forms a conscious intention to listen to a particular conversation, the listening, from a physiological perspective, is never passive, because two muscles within the middle ear allow it to focus on particular frequencies and protect it from sudden loud sounds. In most people, most of the time, this muscular adjustment, which makes the auditory zoom possible, occurs automatically and unconsciously. When loud sounds occur, the zoom shuts them down reflexively. However, the zoom can sometimes come under partial conscious control, as when we attempt to tune in to an important conversation in a very noisy room or learn a second language.

The first of the two muscles is the stapedius. When it tenses, it increases the perception and discrimination of the medium-high-frequency sounds of language, while muting the lower tones that overwhelm higher frequencies, allowing the listener to extract speech sounds from the environment. The second muscle is the tensor tympani, which modifies the tension of the tympanic membrane (the eardrum). It complements the stapedius, and when it tenses, it decreases the perception of low-frequency sounds in background noise. Both of these middle ear muscles contract when we speak, so that we don't injure our ears with the sound of our own voices. This happens not only with opera singers; a child screaming is about as loud as a passing train. Tomatis also observed that when these muscles do not work well, because they are weak, as is the case with many children, they receive too much of the low frequencies (and thus too much background noise) and not enough of the higher frequencies of speech.

These muscles of the middle ear, which tune in on speech, are regulated by the brain. As studies by the neuroscientist Jonathan Fritz and his colleagues from the University of Maryland show, when particular frequencies carry important information (in an experiment, it might be a tone indicating that a shock will soon follow), the brain map areas for those frequencies in the auditory cortex grow within minutes, to better tune in on them. When the frequencies stop, the brain map areas may revert to their previous size or, sometimes, persist. Thus the auditory zoom has a neuroplastic component.

Many children who have had chronic ear infections have hypotonia (generalized low muscle tonus) of the ear muscles. Hypotonia throughout the body is common in children with developmental delays. This overall low muscle tonus also affects their ear muscles, so they cannot focus on specific sound frequencies. Thus they only hear non-differentiated noise, muffled sounds, or too many sounds at once, so their auditory cortices never get clear signals and cant develop normally. That was what happened to Paul: because everything he heard was muffled, everything he said was mumbled, and his auditory brain maps were poorly differentiated. Many children on the autistic spectrum have problems with the auditory zoom as well.

Tomatis realized he could use the Electronic Ear to exercise the auditory zoom by manipulating sounds. For people with non-differentiated auditory maps, he played sound frequencies that would alternately stimulate and relax the slack ear muscles and the brain circuits involved, to give them a workout. People listening to his modified music were being trained to make more differentiated brain maps, and with them, they could start to differentiate speech from background noise.

Speaking Out of One Side of Our Mouths

Tomatis made yet another major clinical discovery—something we all look at every day of our lives, but never see. He discovered that almost every human being talks primarily out of one side of the mouth. People with good listening skills overwhelmingly speak with the right side of the mouth, and the sound of their speech enters their right ear. The right ear and its circuits are also important for singing. All the professionally successful singers that Tomatis examined—with one exception—were "right-eared"; when he played noise into their right ear, so they couldn't hear their voices on the right, their singing voice deteriorated.

The left hemisphere is the area where most people—be they right or left-handed—process important verbal elements of speech. However, each brain hemisphere gets most of its sound input from the ear on the opposite side of the body.* Hence most of the nerve fibers supplying the left hemisphere come from the right ear. Thus the fastest, most

* According to Tomatis, the right ear sends three-fifths of the fibers of its auditory nerve to the left hemisphere, and two-fifths go to the right hemisphere. Similarly, the left ear sends three-fifths of its nerve fibers to the right hemisphere and two-fifths to the left.

direct nerve pathway to the left hemisphere's language area, for most people, is via the right ear. There are a few exceptions, in some left-handed people.

The day Tomatis and Paul met, as they walked outside the monastery, Tomatis saw that there was more animation on the left side of Paul's face, and more movement on the left side of his lips and mouth when he talked, and that his left side—and left ear—leaned into the conversation. This behavior meant that Paul was hearing speech with his left ear. Sound signals had to take the roundabout, less efficient path to get to his left-hemisphere language area: they had to pass from his left ear to his right hemisphere, then back across, through the middle of his brain, to his left hemisphere. The resulting delay, up to 0.4 second, contributed to Paul's inability to process the speech of others in real time, causing a time lapse whenever he tried to put his thoughts into words and contributed to his tendency to lose his train of thought. This is because, over time, speaking on the left side of the mouth and listening with the left ear can lead to disorganization in a developing brain, contribute to learning disorders that seem unrelated to listening, and give rise to stammering and stuttering.

Most people do certain activities with their right hemisphere, and certain activities with their left. For instance, most right-handers write with their right hand, use a baseball bat on the right side, and use the right hand for activities that require strength, coordination, and control. Their right hand is dominant, and is controlled by the left hemisphere. But Paul, Tomatis observed, used his left hand for some activities, and his right for others, a pattern called mixed dominance, which is typical of people with dyslexia who are left-ear listeners, and which can,

* Some left-handed people who speak well, such as President Bill Clinton, use both sides of the mouth to speak, meaning that they listen on both sides equally. Ninety-five percent of healthy right-handers process key elements of verbal language in their left hemisphere; the remaining 5 percent process them in their right. Seventy percent of left-handers process key aspects of verbal language in the left hemisphere, 15 percent in the right, and 15 percent bilaterally. Since only about 10 percent of people are left-handed, the overwhelming majority of people process language activities on the left. For the small number of left-handed people who have the relevant speech area in the right hemisphere, modern Tomatis practitioners do not train right-ear listening. See S. P. Springer and G. Deutsch, "Left Brain Right Brain: Perspectives from Cognitive Neuro-science" (New York: W. H. Freeman, 1999), p. 22.

thought Tomatis, indicate a brain problem. Because of his mixed dominance, Paul was unable to differentiate brain areas for his right and left hands or to use his hands to do different tasks simultaneously, such as playing the guitar, where one hand strums and the other is on the fingerboard. Such mixed dominance contributed to his overall clumsiness and poor handwriting and even affected his eye tracking when he was reading. Instead of reading from left to right in a systematic way, frequently his eyes strayed back to the midline of a sentence or jumped around the page. To make Paul a right-eared listener and correct his mixed dominance, Tomatis set the Electronic Ear to stimulate Paul's right ear and its circuitry by decreasing the volume to the left.

Paul was not just a slow listener. He often missed what people were saying, Tomatis realized, because he heard too much in the low frequencies and not enough in the higher ones. The reasons were several: First, Paul had visibly low muscle tonus throughout his body, which led to his poor posture, clumsiness, and dislike of fast movements. This bodily hypotonia affected and weakened Paul's ear muscles and auditory zoom, so it couldn't differentiate the frequencies of human speech. Second, Paul listened mostly with his left ear. Tomatis had found that the right ear and its brain circuit generally hear more of the higher speech frequencies than the left. Thus Paul often heard more background noise and hum than clear speech. Since the right ear and its auditory cortex normally process the higher frequencies, stimulating the right side also trained Paul's brain to process speech more clearly.

Training the Brain by Stimulating the Ear

Tomatis divided his listening program into two phases. The first, the passive phase, usually lasts fifteen days. It is called passive because the client needs only to hear the modified music, without concentrating on it. (In fact, it's best if he doesn't pay too close attention to the music, because that activity can trigger the old listening habits that the therapist is trying to overcome.)

Mozart's music is usually modified with the filters emphasizing high frequencies, so it often has a whistling, hisslike sound. With children and adolescents, the mothers voice, filtered to accentuate the higher frequencies, is also added. In the early stages of the listening, the mothers voice is so filtered that it is very hard to identify and sounds more like a squeaky whistle, from another world. When the mothers voice is not available, the music alone will suffice. (In the passive phase, the microphone attached to the Electronic Ear is not used. The child simply listens to the music or the mothers voice through headphones.)

The Electronic Ear, defined by Tomatis as a "simulator of proper listening," is composed of two audio channels. One channel feeds the client music that is filtered to emphasize higher treble frequencies and deemphasize lower frequencies. (The higher frequencies are the frequencies of human speech.) The channel with the lower frequencies replicates the hearing that a poor listening ear, with poor muscle tone, experiences. When this channel is played to people with listening problems, their ear muscles "relax," and they replicate their usual listening habits. The filter is always switching between the high-frequency channel and the lower-frequency one, with the volume of the music triggering this switch between channels. When the volume is low, the low-frequency channel is heard; when it gets up to certain decibels, the high-frequency channel kicks in. Each time it switches to the high-frequency channel, the ear muscles and high-frequency listening are exercised; when it switches back to the lower frequency, the muscles and the neurons related to those frequencies can rest. These cycles of exercise make up the passive phase of the listening training.

This switching back and forth between channels triggered by the music's changing its volume (called gating by electronic engineers) injects a sense of novelty into the listening, and novelty is a powerful way to engage brain plasticity. Having a novel sensory experience awakens the brains attention processors, and new connections are more easily made between neurons. It secretes dopamine (and other brain chemicals) to consolidate the connections between the neurons that recorded the event. This transaction is the brain's way of saying "Save that one!" Over the years Tomatis made sure that the gating, or switching back and forth, was not predictable, because surprise is key to brain change. He found that prerecorded tapes lacking random changes were not nearly as effective.

The passive phase ends when the filtering, which gradually decreases over time, is completely eliminated from the Mozart and the mothers voice.

Typically a rest period of four to six weeks is scheduled between the end of the passive phase and the beginning of the active phase, so that the client can consolidate, integrate, and practice his listening gains. At this phase in Paul's training, he was listening better and with less effort. All his previous teachers and tutors had told him he had to try harder. Now that his brain was getting the right information, he discovered he needn't work harder to do better, because there was "flow" to his listening.

When the passive phase ended, Tomatis surprised Paul with the suggestion he go to England, instead of returning home. He told him it was so he could learn English—a daunting task for anyone with listening problems. Tomatis wisely orchestrated Paul's adventure so that he could test his new skills away from Castres, the environment that had been so undermining for him. Paul was ecstatic, but also puzzled. Twice before he had tried to learn English in England, failed, and given up. But now he went and was able to make himself understood, connect with people, and enjoy exploring the London of the 1960s. "Everything," he wrote, "seemed surprisingly easy, even the English language."

On Paul's return, Tomatis's next surprise, to reinforce the idea of a new start, was to suggest that Paul enroll in a boarding school near Paris, though Paul had never successfully completed grade ten. He was intimidated, but Tomatis insisted that Paul aim to get the high school diploma—required for university admission—in two years, and he reassured him that if he put as much effort into school as he had put into his listening training and having fun in England, he'd succeed. Going to school near Paris would allow him to continue the next phase of treatment, which would focus on his difficulties expressing himself.

The active phase came next. To learn to express himself better in speech, Paul, wearing headphones, spoke into a microphone and listened to his own voice through the Electronic Ear. Because his auditory processing had so improved, he could now for the first time really listen to his voice, and use his own voice to improve his auditory processing— and to energize himself. He began to pronounce words with close attention, moving his lips and other muscles, while feeling the vibrations of his lips, throat, and facial and other bones that occurred when he spoke. As he sounded out various words, he developed a more fully differentiated proprioceptive awareness—an awareness of the exact position of his lips, tongue, and other body parts. As in a Feldenkrais lesson, he was using awareness to differentiate his brain maps.

Tomatis now encouraged Paul, who mumbled and spoke in a monotone, to hum, pronounce vowels, and repeat sentences to improve his speech flow. Though a speech therapist might have done this work, Paul did it while using the Electronic Ear, with filtered feedback through his headphones. That enriched the medium and high-range frequencies of his voice, making it more vibrant, stronger, more expressive, and richer in timbre. Tomatis, influenced by his own yoga practice, trained Paul to sit ramrod straight and breathe properly. And one day, to Paul's surprise, he went into a bookstore and realized, as he was leafing through a book to look at the pictures, that he was actually reading and understanding it.

To improve Paul's reading, writing, and spelling, Tomatis asked him to read aloud, while consciously tracking the words with his eyes and listening through the Electronic Ear. To reinforce the newly established neural pathways, Paul also read aloud without the Electronic Ear for thirty minutes a day while making a fist with his right hand and pretending it was a microphone, and reading into it. That simple technique bounced sound off Paul's fist and back to his right ear, reinforcing right-sided listening and the dominance of higher frequencies.

At the boarding school, Paul, despite his fear, made friends quickly and no longer felt like a lost soul. Each weekend he bused into Paris to work on his listening skills. That first year he took and passed his driver's test—the first test he had ever passed. As the school year unfolded, he found that school went from being impossible to being merely difficult. Each day he did his Tomatis homework assignments, reading aloud. As the world of words opened up to him, he found that in his spare time he had switched from drawing to writing poetry. Humbled that he was twenty years old and still in high school, he buckled down and passed his graduation exam, which in France most students fail on the first try. Now Tomatis asked him about his plans. Paul said his new goal was to help others as he had been helped: he wanted to become a psychologist and study with Tomatis.

A long apprenticeship began, with Paul living in the Tomatis home (where Tomatis's office was) from age twenty to twenty-three. By day, Paul's room was an office for a psychologist; by night, it was his bedroom. Paul began university and helped at Tomatis's clinic, learning how to filter music, record mothers' voices, and assist learning-disabled clients. Eventually he became a senior member of Tomatis's team. Tomatis brought Paul into his personal life and invited him to dine with the family and guests—opera singers, musicians, artists, scientists, psychoanalysts, philosophers, and religious figures from all over the world—making university seem dull by comparison. Paul completed his psychology degree at the University of Paris, at the prestigious Sorbonne, and became licensed in 1972.

Paul's first assignment from Tomatis was to start a listening center in Montpellier, in the south of France, and then another one in South Africa. After Tomatis had a heart attack in 1976, Paul came back to Paris to help train practitioners and co-teach with Tomatis. Together they traveled throughout Europe and Canada. In addition, during this period, Tomatis wrote La nuit uterine (The Prenatal Night), a book about the prenatal roots of human language development, and the brain circuits involved in listening. Even though neuroplasticity was not yet accepted in neuroscience, Tomatis began to declare, "Le cerveau est malleable"—the brain is malleable.

Paul, who as a young boy could barely communicate, was now lecturing in several languages, eloquent in both English and French. With his new "ear," he was able to learn Spanish quickly. The boy who once could barely organize himself helped set up thirty centers in Mexico, Central America, Europe, South Africa, the United States, and Canada. From 1979 to 1982, Tomatis came to live in Toronto for six months a year, and helped set up the Listening Centre there, with Paul and the psychologist, Tim Gilmor as co-directors. Paul found Toronto a welcoming city and settled there, where he would take what he learned in France to new levels, to help some of the most challenging cases of arrested brain development.