1. A method for concatenating words in a text string, performed at an electronic device having one or more processors and memory storing one or more programs for execution by the one or more processors, the method comprising: obtaining phonemes for a text string, the text string comprising at least a preceding word and a succeeding word to be concatenated; identifying a last letter of the preceding word to be concatenated, and identifying a first letter of the succeeding word to be concatenated; selecting a connector term and a connector term type based on the identified last letter and the identified first letter; and creating a modified text string for speech synthesis including the selected connector term and the selected connector type.