V-Blaze and V-Cloud Online Help

Confidence Scores

"Clarity" scores refer to the confidence scores generated by V-BlazeV‑Blaze. Confidence is an estimate of the probability that the correct words were selected during decoding. V‑Blaze provides a "confidence score" between 0 and 1 for the text that is produced. Confidence score is a measure of the system’s confidence that the output was transcribed correctly. This provides a very effective mechanism for filtering output. Confidence scores are available at the word, utterance, and call level.

Confidence is calculated for each word, then averaged up to the utterance level, then up to the call level. Confidence scores tend to decrease as calls become more noisy, and as the overall speech signal moves further away from the speech used to train the Voci acoustic and language models. Noise, compression artifacts, and accents all contribute to lower confidence scores.

Confidence Scores Comparisons Between Models

The confidence score is not an accuracy measure. It is a measure of how confident the ASR engine is that it has selected the word most likely to be correct out of all the words it believes a region of speech could represent. The confidence score is only relevant to the model being scored and should not be used to measure performance across multiple models. To measure performance across models, perform accuracy comparisons (described in Measuring Accuracy) against a reference set of data for each of the models.

A confidence score on its own is not meaningful unless you have alternative results to compare against, either from the same recognition operation or from previous recognitions of the same input. Confidence values are relative and unique to each recognition engine. Confidence values returned by two different recognition engines cannot be meaningfully compared. A speech recognition engine may assign a low confidence score to spoken input for various reasons, including background interference, inarticulate speech, or unanticipated words or word sequences.