What is a water whistle?

A water whistle is a device that produces sound when water flows through it, typically used for signaling or alerting. It often consists of a chamber that contains water and an opening where air can escape, creating a whistling sound as the air pressure changes. Water whistles are commonly found in various applications, including toys, safety equipment, and some Musical Instruments. They can be simple in design, relying on the basic principles of fluid dynamics and acoustics.