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Abbreviation for decibels adjusted. Weighted absolute noise power, calculated in dB referenced to 3.16 picowatts (-85 dBm), which is 0 dBa. (188) Note: The use of F1A-line or HA1-receiver weighting must be indicated in parentheses as required. A one-milliwatt, 1000-Hz tone will read +85 dBa, but the same power as white noise, randomly distributed over a 3-kHz band (nominally 300 to 3300 Hz), will read +82 dBa, due to the frequency weighting. Synonym dBrn adjusted.