US Patent 10023298 Propeller sound alteration for a drone

Techniques for using an unmanned aerial vehicle (UAV) to deliver a payload while reducing and/or altering sound generated by the UAV during delivery may be provided. For example, during delivery, the UAV may be instructed to utilize one or more sets of propellers of different sizes to reduce and/or alter the sound generated by and/or around the UAV. Intrinsic and extrinsic information associated with the UAV may be utilized to dynamically adjust the particular sets of propellers of a certain and different size to utilize during different portions of a flight path while delivering the payload.