[jjeaff]

Ya, and restricting airflow reduces load. It may not be intuitive, but you can plug a vacuum cleaner into a meter and put your hand over the tube to restrict airflow. The load on the fan will go down because less air means less friction. In other words, it's easier to run a fan inside a vacuum. The louder sound you get when you put your hand over a vacuum cleaner tube is the motor speeding up because it has less load.