What is STT and TTS?
What is STT and TTS?
Humans naturally communicate through speech. Most voice AI systems, however, process language as text internally.
To bridge this gap, voice AI relies on two core technologies:
Speech-to-Text (STT) — Converts spoken words into text.
Text-to-Speech (TTS) — Converts text into spoken words
This is one of the reasons voice interfaces can feel more natural and efficient than typing.
Why are STT and TTS needed?
Large Language Models (LLMs) don't understand raw audio.
They process text tokens, not sound waves.
When you speak to a voice assistant, your voice must first be converted into text before the AI can understand your request. Once the AI generates a response, that text must then be converted back into speech for you to hear.
Without STT and TTS, voice conversations with AI wouldn't be possible.
Converting speech into text in real time is a challenging task. To measure this, speech recognition systems use a metric called Word Error Rate (WER). It measures the percentage of words that are substituted, deleted, or inserted incorrectly during transcription. A lower WER indicates a more accurate Speech-to-Text system.
STT Providers: Several companies provide Speech-to-Text models-OpenAI Whisper, Deepgram, Google Speech-to-Text, Amazon Transcribe
TTS Providers: Popular providers include ElevenLabs, OpenAI, Google Cloud Text-to-Speech, Amazon Polly, PlayAI
This is one of the reasons voice interfaces can feel more natural and efficient than typing.
Why are STT and TTS needed?
Large Language Models (LLMs) don't understand raw audio.
They process text tokens, not sound waves.
When you speak to a voice assistant, your voice must first be converted into text before the AI can understand your request. Once the AI generates a response, that text must then be converted back into speech for you to hear.
Without STT and TTS, voice conversations with AI wouldn't be possible.
Converting speech into text in real time is a challenging task. To measure this, speech recognition systems use a metric called
Word Error Rate (WER). It measures the percentage of words that are substituted, deleted, or inserted incorrectly during transcription.
A lower WER indicates a more accurate Speech-to-Text system.
STT Providers: Several companies provide Speech-to-Text models-OpenAI Whisper, Deepgram, Google Speech-to-Text, Amazon Transcribe
TTS Providers: Popular providers include ElevenLabs, OpenAI, Google Cloud Text-to-Speech, Amazon Polly, PlayAI
Humans naturally communicate through speech. Most voice AI systems, however, process language as text internally.
To bridge this gap, voice AI relies on two core technologies:
Speech-to-Text (STT) — Converts spoken words into text.
Text-to-Speech (TTS) — Converts text into spoken words
