I wouldn't consider the EC-145 very quiet, especially in flight they have a very characteristic sound.
I hear them passing by a lot, as we have four of these flying medical service, aptly registered as PH-ULP (Hulp=Help), PH-MMT (Mobile Medical Team), PH-MMA (Medical Air Assistance) and PH-EMS (Emergency Medical Service)
Good to see a new FsX model coming!