1. A method for phonetically annotating text, comprising: at a device having one or more processors and memory: identifying a first polyphonic word segment in a text input, the first polyphonic word segment having at least a first pronunciation and a second pronunciation; determining at least a first probability for the first pronunciation and a second probability for the second pronunciation; comparing a difference between the first probability and the second probability with a predetermined threshold difference; and selecting the first probability as a current pronunciation for the first polyphonic word segment in accordance with a determination that the difference between the first probability and the second probability exceeds the predetermined threshold difference.