What Is a Confidence Score in Speech Recognition?

Direct definition

A confidence score is the recognizer’s own estimate that a word or segment is correct. It is not an independent accuracy measurement and is not comparable across vendors without a shared calibration study.

The sections below explain how confidence score is used in transcription and subtitle work, what people often mix up, and which VideoText workflow applies when the next step is a file or review pass.

Key takeaways

• High confidence can still be wrong, especially on names.
• Do not average confidence scores from different APIs.
• Use low-confidence spans as a review queue, not as a published accuracy rate.

How confidence is used

Some pipelines highlight low-confidence words for a human. That is a workflow heuristic. It does not replace word error rate on a labeled set.

The thing people often get wrong

Reporting “average confidence 0.94” as “94% accurate” confuses a model’s softmax with measured error.

Related terms

• word error rate
• transcription accuracy
• transcript QA
• All glossary terms

Sources

1. NIST: Speech recognition evaluation concepts (Open Speech Analytic Technologies overview)