Here, we will give some general information about TTS algorithms. It is not our ambition to thoroughly tackle the different components of the field, which is quite a complex task and requires cross-domain knowledge in areas like linguistic or signal processing.

We will stick to the following high-level questions: what makes a TTS system good or bad? How is it evaluated? What are some traditional techniques, and why does the field need to move toward deep learning? We will also prepare for the next sections by giving a few basic pieces of information on spectrograms.