Methods of self-calibrating of a hearing device and related hearing devices are provided. A method for self-calibrating of a hearing device (which includes an ear canal microphone, an external microphone, and a receiver) includes: obtaining an input signal with the external microphone; providing an output signal with the receiver; measuring the output signal using the ear canal microphone; predicting an output response based on a gain setting; determining a difference between the predicted output response and the measured output signal; and calibrating the hearing device by controlling a gainparameter based on the difference.