A network based interactive speech system responds in real-time to speech-based queries addressed to a set of topic entries. A best matching response is provided based on speech recognition processing and natural language processing performed on recognized speech utterances to identify a selected set of phrases related to the set of topic entries. Another routine converts the selected set of phrases into a search query suitable for identifying a first group of one or more topic entries corresponding to the speech-based query. The words/phrases can be assigned different weightings and can include entries which are not actually in the set of topic entries.