Eh infatti . Vedo che l ' operazione per screditare riuscita benissimo <| sep |> Thank you for your response . It is very thorough . Also now that I think about it it ' s sort of foolish to think of the secret police Gestapo in such a way that they ' re driving around with lights and sirens . Although when you really think about it , it isn ' t that much of a stretch that they would invent a special siren tone for themselves , or something of that nature . Your explanation makes sense to me , and I had actually suspected that perhaps that siren was used in a western film and associated with the Nazis because of that . I couldn ' t remember what one , but I had a vague recollection about it . But just because something was used in a movie , doesn ' t mean it didn ' t have basis in reality , thus why I asked my question . I actually had the chance to speak with an expert on emergency vehicle history , an older man who has been in the field since the 70 s . He told me that if anything the REVERSE of this trope is true , sort of , and that people may be getting confused even further . He said that the hilow siren that is common on European emergency vehicles was instituted as a CONTRAST from the commonly known siren sound used by air raid sirens . During and especially after WWII , the sound of a regular ambulance or police car ' s siren would sound too similar to an air raid siren and people would head for the bunker . So if anything , the hilow is to differentiate an emergency vehicle from the air raid siren a siren associated with luftwaffe bombing raids .