TL;DR: Collabora is building the best natural-sounding Open Source speech synthesis solution which is ready for commercial use – based only on properly licensed speech datasets and unrestricted Open Source code. The exceptional accuracy and multilingual capabilities of these models were striking, yet Google's SPEAR TTS solution used custom models for speech transcription and semantic token extraction. WhisperSpeech's innovative architecture takes its inspiration from the Whisper speech recognition model and reverses its operation to move from transcription to text-to-speech synthesis.