Speech Synthesis

Speech synthesis is the artificial production of human speech.

Accessibility

Speech synthesis helps people with disabilities to communicate with their devices.

Travel and Tourism
- Help get from point A to point B
Automotive Manufacturing
- Read-aloud reports (emails, texts)
E-Learning
- Bring static content like ebooks, pdf or other documents "to life"
Customer support
- Interactive Voice Response System, offers customized messaging to customers
Virtual Assistants
- Voice interactions

Preprocessing involves going through the text and cleaning it up so the computer makes fewer mistakes when it actually reads the words aloud.
Use statistical approach (language models) or neural networks to arrive at the most likely normalized form.
Preprocessing also has to tackle homographs, words pronounced in different ways according to what they mean.

Concatenative TTS relies on high-quality audio clips recordings, which are combined together to form the speech.
At the first step voice actors are recorded saying a range of speech units, from whole sentences to syllables that are further labeled and segmented by linguistic units from phones to phrases and sentences forming a huge database.
During speech synthesis, a Text-to-Speech engine searches such database for speech units that match the input text, concatenates them together and produces an audio file

As any good actor can demonstrate, a sentence can be read in different ways depending on the meaning of the text, the person speaking and the emotions it wishes to express. In linguistics, this idea is known as prosody and is one of the most difficult problems for voice synthesizers.