Abstract: A system and method for testing hearing or for testing and fitting hearing aids is provided, which includes at least one, and preferably a plurality of, compound multi-channel dynamic filters. The system is equipped with earphones, enabling the test operator to hear sounds transmitted to the subject simultaneously with the transmission. A signal is transmitted to the test operator that representing a condition in the patient's ear canal or canals. The test operator modifies the signal using the filter or filters to produce a transmitted signal conforming to and indicating the hearing loss of the subject. This information may then be used to adjust or fit a hearing prosthesis as appropriate, and can also be used to recognize a situation in which the subject's hearing is normal but the subject has lost capability to process sounds.