Why do kettles whistle?

It is presumed that kettles produce a ‘whistle’ because of the vibrations that are produced by built-up steam. Indian aeroacoustics scientist and a lecturer at the University of Cambridge Engineering Department, Anurag Agarwal, and his student Ross Henrywood have identified the source of the sound by deducing two separate mechanisms for it.

Agarwal and Henrywood made a series of simplified kettle whistles and tested these in a rig, forcing air through them at different speeds. They recorded the sounds they produced and succeeded in noting the frequency and amplitude of the sound thus produced. Effective calculations helped them to identify trends in the data. Then, using two separate microphones, they recorded the sounds the steam produced in the kettle, helping them to distinguish the kettle’s ‘whistle’ from the hair dryer’s whoosh!