Kettles are a synonym of calmness. They produce a distinct range of sounds: from the ignition of the heating system, to the water reaching its boiling state and finally the whistle of steam indicating the end of its process. The spectrum of sounds portrayed means that a lot of sound energy and frequencies are involved in the process. In order to minimise disturbance, overall levels should aim to be reduced whenever possible by isolating the boiling sound from the outside and ensuring that what does get projected through the ‘whistle’ is not overly tonal or present.