Nicole Kidman and Keith Urban have a new baby, courtesy of a surrogate ... TMZ has learned. Sources tell us ... the baby was born at Centennial Medical Center in Nashville on December 28, 2010.
Quick Answer. When talking about dishwashers, decibels refers to the noise level a dishwasher produces when it is in operation. The quietest dishwashers have decibel ratings around 40 and slightly below, while the noise level in decibels of a normal conversation is about 60.
The A-weighting filter curve is defined from 20 Hz to 20 kHz. This is intended as a rough replica of the 40 dB loudness of the curve of  equal-loudness contours  for low frequencies. That means, the cutoff low frequencies are really not measured. The display value will really be lower.