A peripheral access module transports voice and data between the common control equipment and the peripheral equipment of a telephone switch. Circuitry is coupled to the transducer for outputting an electrical signal such that the microphone has a main lobe directed forwardly and attenuates signals originating from the sides. The second driver controls a voltage of a third node, according to the first power source, a start signal or a carry signal of a previous stage supplied to a first input terminal, a carry signal of a next stage supplied to a fourth input terminal, and the voltage of the second node.