Speech and Audio Models: Four Years from Whisper Rewriting Open ASR to ElevenLabs Consolidating Voice APIs
Speech models split into two lines. Whisper led ASR: its MIT-licensed 1.55B model drove transcription cost toward zero in September 2022; after v2, v3, and turbo cut the decoder from 32 layers to four, OpenAI moved to closed gpt-4o-transcribe. In TTS, ElevenLabs grew to an $11B valuation and $500M ARR, while Kokoro (82M, Apache-2.0) and Chatterbox preserved self-hosting. Speech-to-speech Realtime APIs are now rewriting live conversation.