A speech synthesizer converts computer based text (usually ASCII- American Standard Code of Information Interchange) into the spoken word. Text-to-speech technology transforms ordinary text into natural-sounding, highly intelligible speech. Speech synthesis is widely used by blind and other handicapped persons to make use of computer technology.
Now, synthesized speech is also used in a wide range of commercial applications to tell us the phone numbers we request when we dial Information, to announce station stops, to vocalize instrument readings, and so on. The speech synthesizers used to give instrument readings and to make brief informational announcements vocalize pre-stored speech.
A speech synthesizers converts ASCII text into speech in real time, by stringing together phonemes according to an algorithm that encodes rules for the relation of English spelling to English pronunciation. Such algorithms can be extremely sophisticated. It first parses sentences and words, then checks for any matches in a stored dictionary; if no match is found, it invokes rules for converting letters to phonemes, then applies prosodic rules for speaking in phrases and finally applies rules for converting phonemes to speech.
It provides the highest level of speech quality and accuracy, producing clear, correct pronunciation of single characters, words even homograph pronunciations, phrases, and proper names.