What is the effective warning distance and decibel level of a hand-crank siren?

The loudness and effective warning distance of hand-crank sirens depend on mechanical structure,wind wheel size and operating speed.Most conventional hand-crank siren models deliver a stable loudness ranging from 100dB to 120dB under standard operating conditions with uniform cranking speed.In open and barrier-free environments,the effective audible warning distance can reach 800 meters to 1500 meters.In complex environments with buildings,forests or noise interference,the effective propagation distance will be reduced appropriately due to sound attenuation and blocking.Continuous and uniform cranking speed is the key to maintaining stable loudness and maximum warning distance.Too fast or intermittent cranking will cause unstable air vibration,resulting in fluctuating sound loudness and shorter effective transmission range.The purely mechanical structure ensures consistent sound output without volume attenuation caused by power drop.