I use a Class 1 Bruel & Kjaer 2270 G4 sound analyzer equipped with a Type 4955a microphone with a dBA-weighted dynamic range of below 6 dBA and up to 110 dBA. All tests are conducted inside a hemi-anechoic chamber with close to 6 dBA noise floor and at 25–28 °C ambient. The test subject is placed a meter from the sound analyzer.
Full & 70% Speed
Speed (Percentage) – Noise
I use a different setup to drive the fan for noise measurements, so there might be a difference in the readings of the Longwin machine, especially in the max fan speed reading.