What is Speech AI?
Speech AI encompasses AI technologies that process and generate human speech, including speech-to-text (STT/ASR), text-to-speech (TTS), voice cloning, and speech translation. These systems enable natural voice interaction between humans and machines.
Why It Matters
Speech AI powers voice assistants (Siri, Alexa, Google Assistant), real-time meeting transcription (Otter.ai, Google Meet), accessibility tools for the visually impaired, podcast production, and the growing trend of voice-first AI interfaces. With GPT-4o and Gemini 2.0 supporting native voice, speech is becoming a primary modality for AI interaction.
How It Works
Speech-to-Text (STT / ASR — Automatic Speech Recognition):
- Converts spoken audio into written text
- Modern systems use transformer-based models (e.g., Whisper by OpenAI)
- Steps: audio preprocessing → feature extraction (mel spectrograms) → sequence-to-sequence model → text output
- Handles multiple languages, accents, and background noise
Text-to-Speech (TTS):
- Converts written text into natural-sounding speech
- Modern systems produce near-human-quality voices
- Approaches: neural vocoders (WaveNet, VITS), diffusion-based TTS
- Can be conditioned on speaker identity, emotion, and prosody
Voice cloning: