Out-of-Vocabulary Word Detection in Speech Recognition

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Solution Overview

Problem

Existing automatic speech recognition (ASR) systems face challenges in efficiently detecting and addressing out-of-vocabulary (OOV) words, which include proper nouns, mispronunciations, and accented words.

Innovation Solution

The system detects OOV words by receiving audio input, determining the characteristics of the OOV word, generating potential word candidates based on context and ranking criteria, presenting these candidates to the user, and allowing the user to select and add the intended word to the repository of recognized words.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the repository of recognized words is kept limited in size, then the system operates efficiently with fast processing, but the accuracy decreases when encountering OOV words like proper nouns, company names, and geographic places

Engineering Contradiction:
Improvetranscription accuracyVSAvoidrepository size
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by generating multiple word candidates with predicted pronunciations before final recognition. When an OOV word is detected, the system proactively creates candidate words with phonetic representations stored in a temporary repository, allowing the ASR system to match future spoken instances against these candidates rather than failing to recognize them entirely.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system serves itself by automatically detecting OOV words, generating candidate replacements with pronunciations, and updating its own repository without external intervention. The ASR system autonomously identifies its knowledge gaps and fills them by creating and storing candidate words with phonetic information, enabling continuous self-improvement of its vocabulary.

Inventive Principle:
Principle #25Self-service

2Reliability

If the system maintains a large repository of words to improve accuracy, then more OOV words can be recognized, but the processing time and computational resources increase

Engineering Contradiction:
ImproveOOV word recognition accuracyVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

Instead of uniformly expanding the entire word repository, the system applies local quality by creating and storing candidate words only in the specific context where OOV words are detected. The temporary repository stores candidates with their phonetic characteristics locally relevant to the detected OOV instance, rather than maintaining a globally expanded vocabulary that would increase overall processing time.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system changes parameters by storing not just word forms but also their phonetic representations (pronunciations) in the temporary repository. This parameter expansion allows the system to match spoken OOV words based on sound rather than requiring exact lexical matches, improving recognition accuracy without significantly increasing repository size or processing time.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the system automatically adds detected OOV words to the repository without user confirmation, then the repository expands quickly improving future recognition, but the accuracy may decrease due to adding incorrect words

Engineering Contradiction:
Improverepository expansion speedVSAvoidword accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system implements feedback by presenting generated word candidates to users for confirmation before adding them to the temporary repository. User selections provide feedback that validates or corrects the system's candidate generation, ensuring that only accurate words are added to the repository. This feedback loop maintains high accuracy while still enabling repository expansion through confirmed additions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system replaces the mechanical approach of automatic unverified addition with a hybrid system that uses automated candidate generation followed by user validation. Instead of purely automatic repository expansion, the system substitutes in a verification mechanism where user confirmation acts as a filter to ensure accuracy before permanent addition to the temporary repository.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If the system presents multiple word candidates to users for OOV words, then the accuracy of adding the correct word improves, but the user interaction time increases

Engineering Contradiction:
Improveintended word selection accuracyVSAvoiduser interaction time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system changes parameters by enriching word candidates with phonetic information and pronunciation guidance. Instead of presenting only text-based candidates, the system provides phonetic representations that help users quickly identify the correct intended word, reducing the time needed for accurate selection while maintaining high reliability in word addition.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12272351B2Automatic out of vocabulary word detection in speech recognition
Publication Date: 2025.04.08 CISCO TECHNOLOGY INC
  • US12272351B2 patent drawing
  • US12272351B2 patent drawing
  • US12272351B2 patent drawing

AI summary

Presented herein are systems and methods are presented for detecting out-of-vocabulary (OOV) words in an automatic speech recognition (ASR) system, determining an intended word for the OOV, and adding the intended word to a repository of words. A method may involve receiving audio input data including a series of spoken words; determining that one of the spoken words is an out of vocabulary word absent from a repository of words; generating word candidates based on characteristics of the out of vocabulary word; presenting the word candidates on a display; receiving intended word input data that indicates a selection of one of the word candidates as an intended word for the out of vocabulary word; and adding the intended word to the repository of words. Additionally, one or more devices or apparatuses may be configured to perform such method.