118DB Whistle (Very loud!)
This design is the incredibly loud survival whistle by: jzisa (https://www.thingiverse.com/thing:1179160).
Extracts from jzisa’s design description:
“The whistle actually has two slightly different tones produced at the same time by separate chambers on either side. The two different tones alternate between amplifying and canceling each other out. This variation creates the shrill sound much like a pea whistle that is more attention grabbing and does not get lost as easily over background noise like a single tone whistle could. Unlike a pea whistle however it does not jam if blown too hard and will not freeze up in cold weather. I tested the volume with my decibel meter and it reached 118.7db. The harder you blow into it the louder it is so someone with a stronger lung capacity may reach louder levels. Be careful it can hurt your ears a little bit at that level.”
“For loudest results blow as hards as you can in a burst! The international distress signal with a whistle is 3 long blasts.”