I made a portable Air Horn out of a empty 2-1/2 gallon water extinguisher and a old "Grote" 4 foot air horn off of a cement truck.
Used the handle off the extinguisher to mate to the air horn, then zip tied the horn to the extinguisher body,, used my air compressor to fill to 120 PSI,, Light weight and Very Very loud!! I have used it at sporting events and parades..
If it doesn't scare the bear its big enough to throw at it as you run away or draw a weapon!!
Compared to a small hand held small air horn,, this thing will make ear wax fall out!!!
I will try to find it in storage and post a picture or video..