Abstract: The present invention relates to a method and apparatus for performing selective acoustic signal filtering. The apparatus comprises two acoustic ports, an electrical output port and an acoustic signal processing device, where all three ports have an impedance characteristic. The acoustic signal processing device includes a diaphragm which will manifest vibration in response to an admitted input acoustic signal and generates an output acoustic signal. The signal processing device is characterized by a frequency response such that the spectrum level of the output acoustic signal will have predetermined differences with respect to the input acoustic signal. The frequency response characteristic of the signal processing device may be set and adjusted by the manipulation of the impedance characteristics of either the acoustic output load or the electrical output load.