From the Sept. 2005 Consumer Reports:

"Which dishwasher is quieter: the Quiet Guard 7 or the Quiet Partner
III? Now shoppers can tell for themselves, at least at Sears stores.
The retailer is requiring that every dishwasher it sells ... bear a
sign indicating its noise level ... based on the average 'A-weighted'
decibels (dBA) measured during a dishwasher's run....

"Although the information can help buyers, it isn't ideal. Steve
Orfield, president of Orfield Laboratories ... says there are better
ways than dBA to judge a product's loudness.... Better, in his
opinion, are units of measure known as sones....

"But the best measure of appliance noise and sound quality, Orfield
says, is a human evaluation that goes beyond dBA or sones. For
Consumer Reports noise Ratings, panelists listen to models we've rated
in the past, then compare their noise levels to those of new models as
they run through their cycle. We use similar methods to judge the
noise of refrigerators and air conditioners."

Mark