Term: Fletcher Munson Loudness Curve

Human hearing is increasingly sensitive to both bass and treble frequencies as volume increases to about 85 dB SPL. At lower listening levels low and high frequencies seem to be lower in volume than midrange frequencies. Two scientists, Fletcher and Munson defined and graphed this phenomenon with the Fletcher-Munson Equal Loudness Curve. Mixing and mastering engineers typically set studio monitors to a nominal volume level to take into account this loudness curve.