An alternative procedure is proposed for measuring headphone performance on human ears. Psychoacoustic procedures are replaced with the measurement of sound pressure at the input to the human ear canal. Furthermore, the exposure of each subject to a reference sound field is replaced by prior knowledge of a desired frequency response. Design goals are given for free-field- and diffuse-field-calibrated headphones, and for measurements at the open and blocked ear canal. The new method avoids the uncertainty from a psychometric procedure, and it allows diffuse-field calibration even at pure tones and narrow frequency bands. Also the extra variance from a physical diffuse sound field is avoided