31. A system comprising: one or more processors; memory storing one or more programs, the one or more programs comprising instructions, when executed by the one or more processors, cause the one or more processors to: receive, from a first user device; a first pronunciation for a first named entity; receive, from a second user device, a second pronunciation for the first named entity; store the first and second pronunciations for the first named entity in a shared pronunciation lexicon, receive, from a third user device, audio data representing user speech and a context of the third user device, the user speech including the first named entity in spoken form; and perform speech-to-text conversion on the audio data to generate a textual representation of the user speech, the speech-to-text conversion comprising selecting, for comparison with the audio data, the stored first pronunciation or the stored second pronunciation for the first named entity based on the context.
31. A system comprising: one or more processors; memory storing one or more programs, the one or more programs comprising instructions, when executed by the one or more processors, cause the one or more processors to: receive, from a first user device; a first pronunciation for a first named entity; receive, from a second user device, a second pronunciation for the first named entity; store the first and second pronunciations for the first named entity in a shared pronunciation lexicon, receive, from a third user device, audio data representing user speech and a context of the third user device, the user speech including the first named entity in spoken form; and perform speech-to-text conversion on the audio data to generate a textual representation of the user speech, the speech-to-text conversion comprising selecting, for comparison with the audio data, the stored first pronunciation or the stored second pronunciation for the first named entity based on the context. 41. The system of claim 31 , wherein the instructions further cause the one or more processors to: receive, from a fifth user device, audio data representing a second user speech and a context of the fifth user device; determine a relevant subset of the shared pronunciation lexicon based on the context of the fifth user device; determine a response to the second user speech, wherein the response comprises a second named entity; determine a pronunciation for the second named entity using the determined relevant subset of the shared pronunciation lexicon; and transmit the response and the pronunciation for the second named entity to the fifth user device.