“Drones are cool but rarely quiet. Dotterel is all about making drones quieter and allowing them to capture sounds directly in addition to images and videos. They’ve developed a unique method to lessen the noise of drones by surrounding the propellers with nano-fibre acoustic dampening materials. This technology is referred as “shrouding” and not only reduces noise pollution but provides additional safety measures, such as protection for the UAV”image04-1

http://www.deviceplus.com/inspire/events/the-most-innovative-mems-sensors-and-startups-from-ces-2017/