1. A method for operating a virtual assistant, the method comprising: at an electronic device having a processor and memory: receiving, from a first user device, a first pronunciation for a first named entity; receiving, from a second user device, a second pronunciation for the first named entity; storing the first and second pronunciations for the first named entity in a shared pronunciation lexicon; receiving, 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 performing 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.