Two hundred and fifty years ago the Japanese Zen master
Hakuin asked the question, “What is the Sound of the Single
Hand?” This koan has long served as an aid to meditation
but it also describes our new interaction technique.
We discovered that gentle fingertip gestures such as tapping,
rubbing, and flicking make quiet sounds that travel by
bone conduction throughout the hand. A small wristbandmounted
contact microphone can reliably and inexpensively
sense these sounds. We harnessed this “sound in the
hand” phenomenon to build a wristband-mounted bioacoustic
fingertip gesture interface. The bio-acoustic interface
recognizes some common gestures that state-of-the-art
glove and image-processing techniques capture but in a
smaller, mobile package.