CBS Laboratories has performed a fundamental study of loudness from which several results already have emerged. A new set of equal-loudness contours has been obtained using octave bands of "pink" noise in a simulated living room environment. The CBS Laboratories contours differ radically from the Fletcher-Munson contours. Forward vs. backward inhibition tests were performed, from which a new summation function was deduced. A new duration vs. loudness level function was obtained for octave bands ranging in frequency from 125 Hz to 8 kHz. These data are being incorporated in an instrument for measuring sensory loudness level.