Dishwasher decibels: sears signs indicate loudness.

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, whatever the brand, bear a sign indicating its noise level. The noise information, being introduced this summer, is based on the average "A-weighted" decibels (dBA) measured during a dishwasher's run, says Tom DeSalvo, Sears' Kenmore-appliance engineering manager.

A sound's intensity is usually expressed in decibels. The A weighting factors in frequency (to approximate what the ear hears), and the averaging weighs the length of time the noise lasts. (A loud but brief bang isn't much of a penalty in determining dBA.)

By averaging sound over the entire cycle, including relatively quiet drying along with louder filling and draining, dBA gives buyers a basis for comparison, DeSalvo says. The quietest machines at Sears emit 46 dBA, softer than conversation; the loudest are 69 dBA, about as loud as some vacuum cleaners and hair dryers. Most people won't notice differences of less than 3 dBA.

For uniformity, all dishwashers sold at Sears are tested at the same independent laboratory. A representative from Whirlpool, one of the manufacturers affected by the new requirement, said the company could adapt the dBA information for use at other stores. For now, neither Lowe's nor Home Depot, two major dishwasher retailers, posts noise levels.

"Customers are asking us for this information," says Dean Schwartz, a Sears buyer. As very good washing performance becomes the norm, noise and convenience features have become more important in the buying decision. Schwartz also cites marketing by manufacturers such as Bosch, which focus on low noise level, for the ...