I have a homemade electric moped that needs a horn.
I am considering a number of options, in order of increasing power.
Ding bell, for bike paths and pedestrians, <85 db
little electric horn like a normal moped, 90 db
"serious" electric horn 100 to 105 db
air horn, considering airzound, any others worth mentioning? 115 db
surplus horn ex 1980s buick, 120 db
LRAD area denial beam 152 db
ex soviet military stirling cycle thermoacoustic engine from project Jericho 167 db @ 30 hz, make yourself heard on the nuclear battlefield