Text analysis and language identification for polyglot text-to-speech synthesis

In multilingual countries, text-to-speech synthesis systems often have to deal with texts containing inclusions of multiple other languages in form of phrases, words, or even parts of words. In such multilingual cultural settings, listeners expect a high-quality text-to-speech synthesis system to read such texts in a way that the origin of the inclusions is heard, i.e., with correct language-specific pronunciation and prosody. The challenge for a text analysis component of a text-to-speech synthesis system is to derive from mixed-lingual sentences the correct polyglot phone sequence and all information necessary to generate natural sounding polyglot prosody. This article presents a new approach to analyze mixed-lingual sentences. This approach centers around a modular, mixed-lingual morphological and syntactic analyzer, which additionally provides accurate language identification on morpheme level and word and sentence boundary identification in mixed-lingual texts. This approach can also be applied to word identification in languages without a designated word boundary symbol like Chinese or Japanese. To date, this mixed-lingual text analysis supports any mixture of English, French, German, Italian, and Spanish. Because of its modular design it is easily extensible to additional languages.