Flat weighting

Flat weighting: In a noise-measuring set, a noise weighting based on an amplitude-frequency characteristic that is flat over a frequency range that must be stated.

Note 1: Flat noise power is expressed in dBrn (f₁ - f₂) or in dBm (f₁ - f₂). Note 2: "3-kHz flat weighting" and "15-kHz flat weighting" are based on amplitude-frequency characteristics that are flat between 30 Hz and the frequency indicated.

Source: from Federal Standard 1037C and from MIL-STD-188