A hearing aid processing apparatus includes audio input units that receive input audio; hearing aid signal processing units that generate first and second output signals each having different frequency characteristics, from the input audio received by the audio input units, based on the characteristics of the band pass filter having the greatest bandwidth among virtual band pass filters composing an auditory filter of a listener. A first audio output unit outputs, as an audio, the first output signal generated by the hearing aid signal processing unit to the left ear of the listener; and a second audio output unit outputs, as an audio, the second output signal generated by the hearing aid signal processing unit to the right ear of the listener.