The chart below shows a line each for measurements tasken 100 feet away from the center of both the L-1 VWT at AAC, and for a typical portable VWT, VR Skydive. This shows how much more quiet the L-1 design is when compared to a propeller type VWT.

Note that during these measurements we did not know the power setting of VR Skydive. We do know that it was approximately 10 MPH slower than the L-1 when this measurement was made. Also note that VR Skydive has a 6 foot wide jet while the L-1 at AAC has a 12.5 foot diameter jet. At the same airspeed the L-1 moves 4.34 times as much air as VR Skydive