1. A system comprising: a processor; and a computer-readable medium operably coupled to the processor, the computer-readable medium having computer-readable instructions stored thereon that, when executed by the processor, cause the system to in response to execution of an application by the system, define an active topic as a first topic, wherein the first topic includes first text defining a plurality of phrases, a probability of occurrence associated with each of the plurality of phrases, and a response associated with each of the plurality of phrases; receive speech text recognized from a recorded audio signal, wherein recognition of the speech text is based at least partially on the probability of occurrence associated with each of the plurality of phrases of the first topic; identify a phrase of the plurality of phrases associated with the received speech text; and perform the response associated with the identified phrase, wherein the response includes instructions defining an action triggered by occurrence of the received speech text, and further wherein the action includes defining the active topic as a second topic, wherein the second topic includes second text defining a second plurality of phrases, a second probability of occurrence associated with each of the second plurality of phrases, and a second response associated with each of the second plurality of phrases.