I believe this site answers it all very thoroughly:
Someone actually went into the trouble of put ting a duck on an anechoic chamber to answer this great mystery of nature. :-)
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.