A hearing system including a hearing aid device, wherein the hearing aid device comprises a housing part, a connection part and an ear piece connected via the connection part to the housing part, and wherein the hearing aid device comprises; • a first microphone (5,5A) configured to receive a first acoustic signal and provide a first audio signal based on the first acoustic signal, • a signal processor connected to the first microphone (5,5A) and configured to receive the first audio signal and provide an output audio signal based on the first audio signal, • a speaker configured to receive the output audio signal and output an acoustic output signal via the ear piece, • an anti-feedback unit configured to receive the output audio signal from the signal processor and a secondary first audio signal from the first microphone (5,5A), and the anti-feedback unit is further configured to estimate a first feedback response of a feedback path (10,10A) from the speaker to the first microphone based on a feedback algorithm, the received secondary first audio signal and the output audio signal, and wherein the hearing system includes a self-checking unit configured to communicate with the anti-feedback unit, and the self-checking unit is configured to compare the first feedback response with a first feedback input signal, and wherein the hearing system includes a memory unit including the first feedback input signal, where the first feedback input signal is a pre-measure of a feedback response of the feedback path (10,10A) from the speaker to the first microphone (5,5A), and wherein the comparing between the first feedback response and the first feedback input signal is for providing a status on a wax filter provided into the ear piece or an inlet to the first microphone (5,5A) and to a second microphone provided into the housing part, including; • determining within a first frequency range a first maximum signal level of the signal level of the first feedback response and a first maximum reference level of the signal level of the first feedback input signal, • determining within a second frequency range a second maximum signal level of the signal level of the first feedback response and a second maximum reference level of the signal level of the first feedback input signal, • determining a first signal level difference between the first maximum signal level and the first maximum reference level, • determining a second signal level difference between the second maximum signal level and the second maximum reference level, and wherein the wax filter status is ok if the first signal level difference is greater than -2, -4 or -6 dB and the second level difference is greater than -3, -5 or -7 dB, and the first frequency range is between 2.5 kHz and 3.5 kHz, and the second frequency range is between 7.5 kHz and 8.5 kHz. • a first microphone (5,5A) configured to receive a first acoustic signal and provide a first audio signal based on the first acoustic signal, • a signal processor connected to the first microphone (5,5A) and configured to receive the first audio signal and provide an output audio signal based on the first audio signal, • a speaker configured to receive the output audio signal and output an acoustic output signal via the ear piece, • an anti-feedback unit configured to receive the output audio signal from the signal processor and a secondary first audio signal from the first microphone (5,5A), and the anti-feedback unit is further configured to estimate a first feedback response of a feedback path (10,10A) from the speaker to the first microphone based on a feedback algorithm, the received secondary first audio signal and the output audio signal, and • determining within a first frequency range a first maximum signal level of the signal level of the first feedback response and a first maximum reference level of the signal level of the first feedback input signal, • determining within a second frequency range a second maximum signal level of the signal level of the first feedback response and a second maximum reference level of the signal level of the first feedback input signal, • determining a first signal level difference between the first maximum signal level and the first maximum reference level, • determining a second signal level difference between the second maximum signal level and the second maximum reference level, and wherein the wax filter status is ok if the first signal level difference is greater than -2, -4 or -6 dB and the second level difference is greater than -3, -5 or -7 dB, and the first frequency range is between 2.5 kHz and 3.5 kHz, and the second frequency range is between 7.5 kHz and 8.5 kHz.