Systems and methods are described for adding entries to a custom lexicon used by a speech recognition engine of a speech interface in response to user interaction with the speech interface. In one embodiment, a speech signal is obtained when the user speaks a name of a particular item to be selected from among a finite set of items. If a phonetic description of the speech signal is not recognized by the speech recognition engine, then the user is presented with a means for selecting the particular item from among the finite set of items by providing input in a manner that does not include speaking the name of the item. After the user has selected the particular item via the means for selecting, the phonetic description of the speech signal is stored in association with a text description of the particular item in the custom lexicon.