First Nonreciprocal Acoustic Circulator (IMAGE) University of Texas at Austin Caption A circulator for sound. The arrows represent acoustic signals flowing through the device (diameter: ~20 centimeters), which circulates sound in a nonreciprocal fashion: Signals can flow from left to top, from top to right, and from right to left, but not in the opposite directions. This creates one-way communication channels for sound, allowing listeners to hear but not be heard in return. Credit Erik Zumalt, Cockrell School of Engineering, UT Austin. Usage Restrictions <i>Science</i> requires that this cover image is used intact and with the accompanying caption and credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.