Disclosed herein are systems and methods for eardrum acoustic pressure estimation for hearing device applications. A receiver signal is produced through a receiver of a hearing device, or a physical extension of the receiver, placed inside an ear canal of a user. A microphone signal is sensed, in response to the receiver signal, using a microphone placed outside the ear canal. Based on the receiver signal and the microphone signal, a reliability signal of the microphone signal and a feedback-path signal are computed. A spectral representation signal of the feedback-path signal is computed, and a real-ear response signal is computed using a mathematical combination of the spectral-representation signal and the reliability signal. The computed real-ear response signal is used to modify an operational characteristic of the hearing device, or to make a recommendation for modification of an operational characteristic or a physical characteristic of the hearing device.