An apparatus comprising: an electro-acoustic transducer comprising: a diaphragm enabling transduction between acoustic energy and electrical energy; two audio signal conductors (191,192) to enable coupling of the electro-acoustic transducer to a device; and the apparatus being characterized in that it further comprises a separator circuit coupled to the two audio signal conductors, and structured to: employ a threshold voltage to distinguish between a relatively low DC bias voltage placed across the two audio signal conductors by the device and a first relatively high DC bias voltage placed across the two audio signal conductors by the device; in response to the relatively low DC bias voltage placed across the two audio signal conductors, allow an analog audio signal representing a sound to be conveyed between the device and the separator circuit through the two audio signal conductors, and allow an AC component of the analog audio signal to pass through the separator circuit to enable transduction between acoustic energy of the sound and electrical energy of the analog audio signal representing the sound; and in response to the first relatively high DC bias voltage across the two audio signal conductors, operate at least the two audio signal conductors as a digital serial bus to enable a first piece of digitally-encoded data to be exchanged between the separator circuit and the device through the two audio signal conductors. an electro-acoustic transducer comprising: a diaphragm enabling transduction between acoustic energy and electrical energy; two audio signal conductors (191,192) to enable coupling of the electro-acoustic transducer to a device; and the apparatus being characterized in that it further comprises a separator circuit coupled to the two audio signal conductors, and structured to: employ a threshold voltage to distinguish between a relatively low DC bias voltage placed across the two audio signal conductors by the device and a first relatively high DC bias voltage placed across the two audio signal conductors by the device; in response to the relatively low DC bias voltage placed across the two audio signal conductors, allow an analog audio signal representing a sound to be conveyed between the device and the separator circuit through the two audio signal conductors, and allow an AC component of the analog audio signal to pass through the separator circuit to enable transduction between acoustic energy of the sound and electrical energy of the analog audio signal representing the sound; and in response to the first relatively high DC bias voltage across the two audio signal conductors, operate at least the two audio signal conductors as a digital serial bus to enable a first piece of digitally-encoded data to be exchanged between the separator circuit and the device through the two audio signal conductors. a diaphragm enabling transduction between acoustic energy and electrical energy; two audio signal conductors (191,192) to enable coupling of the electro-acoustic transducer to a device; and the apparatus being characterized in that it further comprises a separator circuit coupled to the two audio signal conductors, and structured to: employ a threshold voltage to distinguish between a relatively low DC bias voltage placed across the two audio signal conductors by the device and a first relatively high DC bias voltage placed across the two audio signal conductors by the device; in response to the relatively low DC bias voltage placed across the two audio signal conductors, allow an analog audio signal representing a sound to be conveyed between the device and the separator circuit through the two audio signal conductors, and allow an AC component of the analog audio signal to pass through the separator circuit to enable transduction between acoustic energy of the sound and electrical energy of the analog audio signal representing the sound; and in response to the first relatively high DC bias voltage across the two audio signal conductors, operate at least the two audio signal conductors as a digital serial bus to enable a first piece of digitally-encoded data to be exchanged between the separator circuit and the device through the two audio signal conductors. employ a threshold voltage to distinguish between a relatively low DC bias voltage placed across the two audio signal conductors by the device and a first relatively high DC bias voltage placed across the two audio signal conductors by the device; in response to the relatively low DC bias voltage placed across the two audio signal conductors, allow an analog audio signal representing a sound to be conveyed between the device and the separator circuit through the two audio signal conductors, and allow an AC component of the analog audio signal to pass through the separator circuit to enable transduction between acoustic energy of the sound and electrical energy of the analog audio signal representing the sound; and in response to the first relatively high DC bias voltage across the two audio signal conductors, operate at least the two audio signal conductors as a digital serial bus to enable a first piece of digitally-encoded data to be exchanged between the separator circuit and the device through the two audio signal conductors.