This chart shows the frequency spectrum of the acoustic emissions at the East Air Intake area of the L-1 Vertical Wind Tunnel located at Appalachian Amusement Center. Comparing this to the 2-3-2004 test with the fan blades removed shows how much noise is generated by the fan blades and how much by the fan hub. This helps to determine what improvements can be made. When these measurements were made there was intermittent wind and background noises such as passing vehicles and distant power tools. These may have slightly increased some readings even though great care was taken to make the measurements between occurrences. The zero readings were below the meter's range minimum and so didn't register. The meter was located 56 feet to the side of the fan centerline near the transformer, in exactly the same position as the 1-3-2004 test. Some hum from the transformer contributed to the readings.

The chart below shows the acoustic emissions at 700 RPM, with, and without the fan blades,. The third line shows the difference between these two measurements. This data is being used internally to help determine where the noise is coming from, and what can be done to reduce it.