Here is a strange photo of Emperor Hirohito inspecting some impressive “war tubas” in the 1930s. War tubas were a type of “acoustic locator”:http://en.wikipedia.org/wiki/Acoustic_location for detecting aircraft that pre-dated radar.
Found randomly via “Futility Closet”:http://www.futilitycloset.com/2006/08/28/japanese-war-tuba/. Isn’t the internet wonderful late at night?
*ADDENDUM:* Also see “Dutch”:http://cominganarchy.com/2010/07/13/dutch-war-tuba/, “Russian”:http://cominganarchy.com/2008/03/19/смотреть-russian-war-tubas/, “British”:http://cominganarchy.com/2008/04/13/i-say-there-war-tuba/, and “Canadian”:http://cominganarchy.com/2008/05/24/war-tubas-eh/ war tubas.