Equal loudness measurements were made for 12 young adult ears over a frequency range of 250–6000 Hz. A damped wavetrain signal having a decrement of 0.90 was used and this was delivered by a pair of circumaural earphones. A well-defined but empirical relationship is shown to exist between relative loudness and sound pressure and the mathematical expression is given. Observational accuracy attainable was, when averaged, usually consistent with the calculated values to within about 12 dB over a pressure range of about 0.0001–100 μbars. With this method of measurement comfortable loudness pressure for the normal ear was found to be independent of frequency over the normal frequency range. Damped wavetrains with circumaural earphones appeared to give about four times greater accuracy than pure tones and supraaural earphones for identical measurements.