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Dark alleys are unfriendly environments towards children, women, and elderlies. Threats still lurks among despite the rising caution of public security and widespread surveillance cameras. General whistles require a big blow to send out audible sounds. However in critical conditions people are often scared stiff, let alone forcing out sufficient airflow. Liquid and humidity sensor are used to design this electronic whistle. By touching the mouthpiece with the tongue and completing the current passage, the device then lets out a loud and sharp whistle, making it more efficient to call for help.