Originally Posted By: PureSurvival

the reason is the average person does not understand the process of sound so they perceive that a loud high pitched ear bleeding sound is more effective when they blow a whistle than one with a lower pitched sound

I'm sure thats true.
My point was that a higher pitched sound might attract more attention against background noise than a lower one.

I suspect that whistles are now so common that any other sound wouldn't work as well. If I heard a whistle in the woods I would assume that somebody needed help whereas an air horn I would guess was some construction work, forestry etc.