What about an air horn? This one says it's 115db. You pump it up with a bicycle pump.

https://www.amazon.com/Delta-Airzound-Bike-Horn/dp/B000ACAMJC/ref=pd_bbs_sr_1/105-2339420-5913210?ie=UTF8&s=sporting-goods&qid=1194517539&sr=8-1&tag=viglink20253-20


