Any used filter people know of the kettle, water and burning will produce large noise, and more noisy.
And the voice didn't sound like water and air bubble.
Open to see inside can hear the sound, but in POTS of water is very quiet, only a few air bubbles.
In terms of heating, boiling water with a gas stove basically do not have such a big sound.
Arguably this voice is not the water itself, so from the filter where the sound of the kettle?
This is actually and filter no relationship kettle.
Friction when water temperature rises, the water molecules will gradually increase, friction friction noise, a large number of water molecules but filter kettle generally smaller, and space on the surface of the water in the kettle, sound amplification.
Water temperature reached 100 degrees, the water boils, the water from a liquid into a gas generating steam, there is no friction, voice naturally small.