Rates the ability of the fan to move air at the lowest setting, the most likely setting to be used at night while sleeping. Weak air movement scores 30%, moderate air movement scores 50%, gentle but effective air movement scores 90%, while models considered too powerful on their lowest setting score 70% (strong air movement is less desirable when you're trying to sleep, but can still be compensated for with an extra sheet, for example; weak air movement, on the other hand, is essentially useless). Models with more than three settings such as the DC powered models with 5 and 6 settings earn a 90% score if the first setting is lower than the optimal air movement speed as one of the other 4 or 5 settings will deliver the appropriate air movement.
We measure noise and will make comment if it noteworthy, particularly when conducting the bedroom test (measurement of airflow at lowest speeds) as this would be an area where a noisy or distracting sound from the motor would be an issue. However we are unable to deliver the exact decibel figures collected as the test room's ambient noise levels are not low enough to distinguish the difference in noise levels below 30dB. While the actual sounds a fan make may seem loud or quiet, its the type of noise produced that people often find distracting and these can be produced at noise levels that are still very low.
The test costs to construct an anechoic chamber (a room with a dB below 15) would be prohibitive. However we are looking at better ways to deliver a more useful description of the sounds created by each fan and will add these to the good or bad points.