3-D printed device cracks cocktail party problem

A 3-D printed plastic disk can help pick out a voice from a crowd, a task that is easy for people but not for technology. The device, reported August 10 in the Proceedings of the National Academy of Sciences, could lead to improved voice recognition and hearing aids.

To solve what scientists call the cocktail party problem, Duke University electrical engineer Steven Cummer and colleagues built a pizza pie–sized disk that was divided into 36 wedges and imprinted with centimeters-high hexagonal cells. The heights of the cells varied in each wedge so that incoming sound waves would propagate differently depending on their frequency.

The researchers placed the disk in an echo-free room and installed three speakers that blared random words at the same time. After a microphone at the disk’s center recorded the sound waves that had traveled inward, a computer algorithm successfully identified what was said and from where.