An exemplary sound processor apparatus includes 1) an earhook interface assembly that includes a plurality of contacts and that is configured to interchangeably connect to a microphone assembly and an EAS receiver assembly by way of the plurality of contacts, and 2) a control module communicatively coupled to the plurality of contacts and that is configured to selectively operate in an input mode or in an output mode. While operating in the input mode, the control module uses the plurality of contacts as input ports to receive one or more audio signals detected by the microphone assembly while the microphone assembly is connected to the earhook interface assembly. While operating in the output mode, the control module uses the plurality of contacts as output ports to output one or more EAS signals to the EAS receiver assembly while the EAS receiver assembly is connected to the earhook interface assembly.