A hearing assistance device for measuring sound pressure at a tympanic membrane of a wearer's ear including a high frequency range. The device comprises a processor connected to a sensor in the ear canal. The device provides a measure of the sound pressure level at the tympanic membrane of the wearer using a null frequency and a null Q measured at a distant position away from the tympanic membrane. The system does not require a precise knowledge of the ear canal, nor does it require an elaborate calibration step. In various embodiments, the present approach works at low and high frequencies.
