Duke Students Design Device to Aid Paralyzed Musician

Last fall, Duke biomedical engineering seniors Lindsay Johnson and Corey Weiner pooled their engineering and musical knowledge to design and build a custom electronic device whose big round sensor pads sound electric guitar-like notes when struck by light wooden hammers.

Their hope is that Hamer will be able to play bass string guitar-like riffs with the new made-to-order instrument in the same manner he now plays an acoustic string instrument called the hammered dulcimer, which he took up after losing fine control of his fingers.

"I've been bragging on Lindsay and Corey quite a bit," Hamer said in a telephone interview. "To me, they did graduate student work as undergraduates. I think they did a tremendous amount of work and were tremendously inventive to come up with this thing."

The students and their instructor, Duke assistant biomedical engineering research professor Laurence Bohs, plan to hand over their "hammered bass guitar" to Hamer on Friday.

Hamer was paralyzed from the chest down after breaking his neck in a 1985 diving accident. By use of some cunning innovations, he has nevertheless resumed playing music with a band called The Lemon Sisters and the Rutabaga Brothers as well as with his own Mike Hamer and the Rhinoceroses.

"I have no grip to speak of, but I have good wrists," Hamer said. So, after his injury, he learned a new use for the elastic "universal cuff" that disabled people sometimes employ for eating.

"People whose fingers don't work can stick a fork in there and still feed themselves using their wrist motion," he explained. Hamer's musical innovation was to dangle pencil erasers from a cuff on each hand and use those to thump the keys of an electronic keyboard.

He also taught himself to play the hammered dulcimer by placing peg-like wooden hammers between the two inside fingers of each hand, where "I have enough tension," he said. He can then hammer the strings by using still-functional muscles in his arms.

But Hamer's first love remains the electric string bass, a sound he cannot duplicate by using eraser action on his keyboard. "I can't play very fast," he said. So, several years ago he told Bohs, a fellow musician, that he would like to figure out a way to hook up a bass synthesizer using his dulcimer hammers because then he could play a lot faster.

Hamer's request became one of four projects Bohs assigned to students in last fall's session of his annual course, which challenges biomedical engineering seniors to design and build practical devices in one short semester that could improve the lives of real disabled people.

Both Johnson, of Pittsburgh, and Weiner, of Manalapan, N.J., jumped at the challenge. "This is the only class of its kind that trusts students with such a big responsibility," said Johnson, who is planning to get an engineering job after graduation and perhaps go back to graduate school later. "It's not something that has to work only once during the presentation and then we throw it away," added Weiner, who plans to attend medical school. "It is something that will actually be used, hopefully for a long time."

Johnson, who has studied piano since the age of 4 and also plays "some" flute, percussion and guitar, was able to draw on her own musical background in working with Weiner and Hamer to design the hammered bass. Their research took them to a wedding in Chapel Hill where they videotaped Hamer in action. They also asked him to hammer on the palms of their hands to gauge the power of his swings.

Flinging pencil erasers at the piano-sized keys of a normal keyboard synthesizer left a lot to be desired, Johnson said. Keys that narrow made him more prone to making mistakes, she said. And the erasers also produced a suppressed sound. With the students' hammered bass design, "he'll be doing multiple motions with his arms as well as his wrists," she said. "Using his dulcimer hammers, he will be able to play with more freedom, speed and accuracy."

Hidden inside the hammered bass's black acrylic cover are three electronic devices called MIDI Brains. MIDI is an acronym for Musical Instrument Digital Interface, a language that electronic musical instruments communicate in, Weiner said. These "brains,"one for each eight of the 24 sensor pads, "translate" each hammer hit on each pad into a musical note.

The pads themselves include "piezoelectric" materials that convert pressure into an electronic signal. Their round shape and 1 -inch diameter dimensions are more suitable than keys to be struck by dulcimer hammers, and they're also arranged to play to Hamer's strengths.

Johnson's and Weiner's device will plug into Hamer's usual keyboard, and it can also be connected to other synthesizers. Their total construction costs were $645, an amount that included the price of a fourth MIDI Brain that went up in smoke during one of their late-night soldering sessions.

Other Duke seniors attending last's fall's class designed three other devices for disabled children, including:

"Bumblemania," a project in which Duke seniors Sam Cho, of Newton, N.C., and Thomas Pawlowski, of Lebanon, Tenn., modified vibrating toys - called bumbleballs - to jiggle in response to noises, a flashlight beam, touch, or a magnet at the end of a "magic wand." The intent is to aid rehabilitation therapists in stimulating the senses of children whose nervous systems have been impaired by head injuries.

The "Portable Sensory Stimulator," a compact kit of switch-activated sensory cues (recorded music and voice commands, flashing lights, pleasant scents and vibrations) intended to help therapists assess children who are recovering from severe head injuries. It was designed and built by seniors Kit Yee Au Yeung, of Hong Kong, China, and Daniel McCormick, of Plymouth, Mass.

The "Talking Clockface Spinner," by Steven Gebhart, of Troy, Ill., and Jennifer Meuchel, of Waldorf, Md., a device designed to help visually and speech-impaired children interact with their teachers during a grade school class exercise called circle time. Teachers insert different objects into positions on the spinner, which resembles a clock face. They also record verbal messages related to each of the objects. The children can involve themselves in the exercises by releasing a button when the pointer reaches the right position.