Dishwasher noise levels are rated in decibels, the lower the decibel number the quieter the dishwasher will be. Although a difference of just a few decibels may not seem to be much, a dishwasher that is just one decibel more is actually 30 percent louder. And a dishwasher that is four decibels more is surprisingly twice as loud! So, the higher the decibel doesn’t mean a quieter machine as you would expect, in fact, quite the opposite.