With low-noise propellers and drones now becoming the craze, here is a We Talk UAV video showing the sound difference between the latest DJI drones:
A sound meter and launch pad were placed in a fixed position, and the drones hovered at the same height as the sound meter for consistent results.
DJI drones:
The Spark gave a reading of 74dB

Mavic Air gave a reading of 76.1dB.

Mavic Pro gave a reading of 79dB, while the same drone with low-noise propellers gave a reading of 75.4dB.

