In 1779 the German- Danish scientist Christian Gottlieb Kratzenstein won the first prize in a competition announced by the Russian Imperial Academy of Sciences and Arts for models he built of the human vocal tract that could produce the five long vowel sounds (in International Phonetic Alphabet notation:, ,, and ). Some early legends of the existence of " Brazen Heads" involved Pope Silvester II (d. Long before the invention of electronic signal processing, some people tried to build machines to emulate human speech. In certain systems, this part includes the computation of the target prosody (pitch contour, phoneme durations), which is then imposed on the output speech. The back-end-often referred to as the synthesizer-then converts the symbolic linguistic representation into sound. Phonetic transcriptions and prosody information together make up the symbolic linguistic representation that is output by the front-end. The process of assigning phonetic transcriptions to words is called text-to-phoneme or grapheme-to-phoneme conversion.
The front-end then assigns phonetic transcriptions to each word, and divides and marks the text into prosodic units, like phrases, clauses, and sentences.
This process is often called text normalization, pre-processing, or tokenization. First, it converts raw text containing symbols like numbers and abbreviations into the equivalent of written-out words. Many computer operating systems have included speech synthesizers since the early 1990s.Ī text-to-speech system (or "engine") is composed of two parts: a front-end and a back-end. An intelligible text-to-speech program allows people with visual impairments or reading disabilities to listen to written words on a home computer. The quality of a speech synthesizer is judged by its similarity to the human voice and by its ability to be understood clearly. Alternatively, a synthesizer can incorporate a model of the vocal tract and other human voice characteristics to create a completely "synthetic" voice output. For specific usage domains, the storage of entire words or sentences allows for high-quality output. Systems differ in the size of the stored speech units a system that stores phones or diphones provides the largest output range, but may lack clarity. Synthesized speech can be created by concatenating pieces of recorded speech that are stored in a database. The reverse process is speech recognition. A text-to-speech ( TTS) system converts normal language text into speech other systems render symbolic linguistic representations like phonetic transcriptions into speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products.
Speech synthesis is the artificial production of human speech. Problems playing this file? See media help.
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