Most of these motorized machines use a pulsatile or pulsating water pumping action at a relatively low, predetermined fixed pulse cyclic rate, designed to match the normal wave rate of healthy, unobstructed nasal cilia.[17] This matched pulse rate is claimed to stimulate the nasal cilia hairs and promote better sinus health, while reducing the severity of allergic reactions.[18] More sophisticated motorized irrigators have two or more pulse cycle settings that adjust the actual pulse cycle (as opposed to a simple volume/speed control, which does not alter the pulse cyclic rate). This design affords the user the option of using a higher pulse cyclic rate when suffering from partially closed sinuses, as in a typical case of acute sinusitis. The efficacy of all motorized pump irrigators has not yet been tested compared to simpler non-motorized mechanical pressure nasal irrigation methods.[19]