Glossary · Assistants and voice

Speech recognition (STT): definition and use

Definition

Speech recognition, in English speech-to-text or STT, converts spoken language into written text. It is the input building block of any voice application: only once what is said exists as text can a system understand it and react. Its quality decides the whole dialogue, because a wrongly recognised word leads to a wrong answer, no matter how good the rest is.

Why the Term Matters

Voice projects often fail not at the clever model behind them but at poor recognition at the start. Dialect, technical terms, background noise and phone quality challenge speech recognition. Whoever takes the block seriously tests it early on real recordings of their own users. That spares the disappointment of building a system that shines in the lab and understands nothing in practice.

When It Is Relevant

  • An application should process spoken language, on the phone or in an app.
  • Dictations or conversations should be turned into text automatically.
  • Technical terms or proper names must be recognised reliably.
  • The audio quality is challenging, for example over the phone line.

When Not

When the input is already text, no speech recognition is needed. A web chatbot works without it. And when the recording conditions are very poor and cannot be improved, expectations should be tempered before much effort flows into downstream logic.

Industries That Use It

  • Medicine and radiology: capture findings by dictation, with recognition that reliably hits technical terms.
  • Justice and administration: turn protocols and hearings automatically into searchable text.
  • Media and broadcasting: transcribe interviews and contributions to process them faster.
  • Call centers: transcribe conversations to capture requests and check quality.

Typical Use Cases

  • The input block of a voice agent that turns speech into text.
  • A dictation system that creates specialist text directly from speech.
  • A transcription of meetings or interviews into searchable text.
  • An analysis of calls that builds on the recognised text.
  • A subtitle or protocol service for recordings and live conversations.

Decision Guide

Decision Guide
SignalSpeech recognition fitsAlternative
Input is spoken languageSTT as the input blocktext form without voice
Technical terms must be righttest adapted recognitiongeneric recognition with risk
Input already exists as textnot neededprocess directly
Audio quality very poorcheck conditions firstimprove the recording

Example

A call center wants to capture requests automatically. In the workshop a narrow use case is chosen, for example recognising typical conversations with their technical terms. Within days a prototype runs on real recordings, making the recognition quality visible before building on it. Only when recognition holds up does further processing follow. This describes the method, not an asserted metric.

Service Connection

The entry is the AI workshop to check quality and conditions, then AI development and AI implementation.

Sources

This framing describes common practice around speech recognition. Recognition quality depends strongly on language, technical vocabulary and audio conditions and should be checked on real material.

Related topics Text-to-speechVoice agentConversational AI

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Frequently asked questions

What is the difference between speech recognition and text-to-speech?
Speech recognition turns spoken language into text, text-to-speech the reverse from text into speech. One block is the input, the other the output of a voice application.
Why does the system recognise technical terms poorly?
Generic models are trained on everyday language. Specialist vocabulary and proper names often need adaptation and a test on the real material of your own users.
How do you check quality early?
With a prototype on real recordings of your own cases. That shows the recognition quality before much effort flows into downstream logic.