Text to speech — Fundamentals of Speech Synthesis + 5 more topics

Speech synthesis, or Text-to-Speech (TTS), generally breaks down into a few key steps. First, the input text needs to be understood: what are the words, how should they be pronounced, and what's the overall structure and emotion? This is the text analysis part. Then, based on that analysis, the system generates the actual sound, which is the acoustic synthesis part.

There are primarily two main approaches to acoustic synthesis:

When a TTS system wants to say a word, it first breaks it down into "phonemes" – the smallest units of sound. Then, the acoustic model takes these phonemes and predicts the actual acoustic properties needed to generate them. These properties are often represented as a sequence of acoustic features, like Mel-Frequency Cepstral Coefficients (MFCCs) or spectrograms, which essentially describe the sound's spectrum over time.

When we talk about text processing and linguistic analysis for Text-to-Speech (TTS), we're generally discussing a pipeline of steps that transform raw text into a format ready for sound generation. This isn't just about reading words; it's about making them sound natural.

First, we need to clean up the text and break it into manageable parts.