S9™ Series H5i™ Heated Humidifier... "noisy"

I think mine is just normal Darth Vader type conductive noise, although it doesn't change with hose position. Getting worse with earplugs and other people not hearing it seems to be pretty indicative of conductive noise. That bird call noise is quite interesting though; thanks for sharing Pugsy. Another thing I remembered...I tried putting a towel under the machine and it made the noise quieter. However, it was a more annoying pitch, so I ditched that idea. Best wishes.