Sunleaves Windtunnels are pretty quiet, no rattle or buzz sound. It's not completely silent. I would suggest considering a Variable Voltage Regulator like this:
http://www.ebay.com/itm/KRM-AEEC-590VR-Variable-Transformer-130VAC-0-5kVA-590VR-Voltage-Regulator-Variac-/330790688474
This way you...