Text-to-Speech (TTS) — From Tacotron to F5 and Kokoro
ASR inverts speech to text; TTS inverts text to speech. The 2026 stack is three parts: text → tokens, tokens → mel, mel → waveform. Each part has a default model that fits in a laptop. You have a string: "Please remind me to water the plants at 6 pm." You need a 3-second audio clip that sounds natural, has correct prosody (pauses, stress), pronounces "plants" with the right vowel, and runs in under 300 ms on a CPU for a live voice assistant. You also need to swap voices, handle code-switched input ("remind me at 6 pm, daijoubu?"), and not embarrass yourself on names. Modern TTS pipelines look like this: Text frontend. Normalize text (dates, numbers, emails), convert to phonemes or subword tokens, predict prosody features. Acoustic model. Text → mel spectrogram. Tacotron 2 (2017), FastSpeech 2 (2020), VITS (2021), F5-TTS (2024), Kokoro (2024). Vocoder. Mel → waveform. WaveNet (2016), WaveRNN, HiFi-GAN (2020), BigVGAN (2022), neural codec vocoders in 2024+. In 2026 the acoustic + vocoder split blurs with end-to-end diffusion and flow-matching models. But the mental model of three parts still holds for debugging. Tacotron, FastSpeech, VITS, F5/Kokoro side-by-side Tacotron 2 (2017). Seq2seq: char-embedding → BiLSTM encoder → location-sensitive attention → autoregressive LSTM decoder emits mel frames. Slow (AR), wobbly on long text. Still cited as a baseline.…
Text-to-Speech (TTS) — From Tacotron to F5 and Kokoro: ASR inverts speech to text; TTS inverts text to speech. The 2026 stack is three parts: text → tokens,…
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