Livewired. David Eagleman

children ranging from two to eight years old. Their parents send me video updates most days. At first it wasn’t clear whether anything was happening. But then we noticed that the children would stop and attend when someone pinged a key on the piano.

      The children also began to vocalize more, because for the first time they are closing a loop: they make a noise and immediately register it as a sensory input. Although you don’t remember, this is how you trained to use your ears when you were a baby. You babbled, cooed, clapped your hands, banged the bars of your crib . . . and you got feedback into these strange sensors on the side of your head. That’s how you deciphered the signals coming in: by correlating your own actions with their consequences. So imagine wearing the chest strap yourself. You speak aloud “the quick brown fox,” and you feel it at the same time. Your brain learns to put the two together, understanding the strange vibratory language.⁴⁴ As we’ll see a little later, the best way to predict the future is to create it.

       Two children using the vibratory chest strap.

      We have also created a wristband (called Buzz) that has only four motors. It’s lower resolution, but more practical for many people’s lives. One of our users, Philip, told us about his experience wearing Buzz at his work, where he accidentally left an air compressor running:

      I tend to leave it running and walk around the room, and then my co-workers say, “Hey, you forgot: you left the air on.” But now . . . using Buzz, I feel that something is running and I see that it is the air compressor. And now I can remind them when they leave it running. They are always like, “Wait, how did you know?”

      Philip reports he can tell when his dogs are barking, or the faucet is running, or the doorbell rings, or his wife calls his name (something she never used to do, but does routinely now). When I interviewed Philip after he’d worn the wristband for six months, I quizzed him carefully on his internal experience: Did it feel like buzzing on his wrist that he had to translate, or did it feel like direct perception? In other words, when a siren passed on the street, did he feel that there was a buzzing on his skin, which meant siren . . . or did it feel that there was an ambulance out there. He was very clear that it was the latter: “I perceive the sound in my head.” In the same way that you have an immediate experience when seeing an acrobat (rather than tallying the photons hitting your eyes), or smelling cinnamon (rather than consciously translating molecular combinations on your mucosal membranes), Philip is hearing the world.

      The idea of converting touch into sound is not new. In 1923, Robert Gault, a psychologist at Northwestern University, heard about a deaf and blind ten-year-old girl who claimed to be able to feel sound through her fingertips, as Helen Keller had done. Skeptical, he ran experiments. He stopped up her ears and wrapped her head in a woolen blanket (and verified on his graduate student that this prevented the ability to hear). She put her finger against the diaphragm of a “portophone” (a device for carrying a voice), and Gault sat in a closet and spoke through it. Her only ability to understand what he was saying was from vibrations on her fingertip. He reports,

      After each sentence or question was completed her blanket was raised and she repeated to the assistant what had been said with but a few unimportant variations. . . . I believe we have here a satisfactory demonstration that she interprets the human voice through vibrations against her fingers.

      Gault mentions that his colleague has succeeded at communicating words through a thirteen-foot-long glass tube. A trained participant, with stopped-up ears, could put his palm against the end of the tube and identify words that were spoken into the other end. With these sorts of observations, researchers have attempted to make sound-to-touch devices, but in previous decades the machinery was too large and computationally weak to make for a practical device.