What is speech synthesis?
Speech synthesis is the artificial replication of natural language. Linguistic utterances are generated by the computer. They are not played back from a previously recorded set of utterances but are generated up-to-date.
How does the voice get into the program?
The first question is what is actually the “synthetic” thing about speech synthesis. A lot of text to speech tools are based on detailed voice recordings by trained speakers. So the voices are not artificial, but were created from the voices of professional human speakers!
This clay material is then divided into small parts, so-called units. These can be individual sounds, so-called phonemes, e.g. A and E, but also diphthongs like EI or AU and even whole syllables. This is important because the same letter can sound different depending on the environment. E.g. the letter E occurs twice in “text to speech”, but it is pronounced completely differently each time.
The units are then concatenative combined into a new, flowing audio text using quite complex algorithms. That is the real synthesis. “Synthesis” means “composition” in the narrower sense. This requires a certain understanding of the text so that the result sounds as natural as possible. There is also the simple rule that the voice should rise when there is a question mark and lower when there is a point at the end of a sentence. But so that a natural language melody (prosody) can also prevail inside the sentence, the program must know where the subject is in the sentence because this word has a stronger emphasis. These analysis methods are of course much more complex.
Example – Murf voiceover studio
Murf is an AI-based text to speech tool. It has 10 languages and more than 60 different voices. The voice over video app is perfect for adding the voice to presentations, videos or images because murf is unlike the other text to speech tools a video editing tool as well. It also has free stock background scores and 15 minutes of free voice over.
