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. In some examples, 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.