A hearing assistance device for measuring sound pressure at a tympanic membrane of a users ear, the device comprising a housing adapted to be worn at least partially in an ear canal of the user a laser source coupled to the housing and adapted to project a beam of laser energy at the tympanic membrane a sensor for receiving reflected laser energy directed at the tympanic membrane, and a processor connected to the sensor and adapted to estimate the sound pressure level and phase at the tympanic membrane from a signal generated from the sensor. Additional examples provide a hearing device for measuring sound pressure at the tympanic membrane using ultrasonic signals. Further examples provide a hearing device for measuring sound pressure at the tympanic membrane using magnetic sources and sensors.
