An ultrasonic humidifier works similar to a stereo speaker, except it stays whisper quiet when powered on! The nebulizer vibrates at an ultrasonic frequency to create mist that easily dissipates into the air, rather than droplets that fall to the ground. Ultrasonic humidifiers are highly effective, but due to the vibrations you may notice fine white dust collecting from high-mineral water. If so, try filtered water or a Crane Demineralization Filter.