Please view the Hand Crank Air Raid Siren pictures on the left and the youtube clip on this page. You will notice that you can turn the fan cover ON or OFF. The default position is COVER ON. You should try cranking the air raid siren with the fan cover on to see if it is loud enough and then slowly crank up speed and turn the handle to OFF. Some people may even need ear plugs!
This siren is well made and extremely loud. While the price is a bit on the high side, I have no doubt we'll be using this at the marina for years to come.
Would buy again and recommend this product.