What Exactly are Whistling Tea Kettles

All tea kettles with an open spout are whistling tea kettles though some tea kettles intentionally place some additional spout covering or contraption which emits a different whistling sound. The whistling sound of a tea kettle depends on the size of the opening of the spout and its neck length. In the process of heating water in a kettle, as the water heats, some of it turns into vapor and this vapor must somehow exit or escape from the pot. As the vapor makes its way to the spout, it produces a hissing sound as it moves from one temperature to another. This hissing sound may vary depending on the structure of the spout. Some spouts have covers which can alter the sound of the vapor. Once the vapor exits the spout, it is transformed into steam. Thus you see a bit of that steam and a lot of that hiss in the kettle. That is how the whistling tea kettle got its name.