bruelandkjaer.targetcurve  this curve was published in the B&Ks paper "Relevant loudspeaker tests in studios in Hi-Fi dealers' demo rooms in the home etc. using 1/3 octave, pink-weighted, random noise".

trained.targetcurve  a curve subjectively preferred by "trained listeners". This curve is a rough (smoothed) implementation of the corresponding curve from the paper "The Measurement and Calibration of Sound Reproducing Systems" by Floyd E. Toole, Consultant to Harman International. 