Network-Based Hypothesis Stitching for Long-Form Speech Recognition

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Solution Overview

Problem

End-to-end automatic speech recognition systems underperform when applied to long-form speech exceeding training data length, leading to reduced accuracy and increased computational costs.

Innovation Solution

Segment audio streams into multiple segments, identify speakers within each segment, perform ASR to generate short-segment hypotheses, merge these hypotheses using stitching symbols, and consolidate them into a single hypothesis using a network-based stitcher, employing alignment-based or serialized stitchers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If end-to-end ASR systems process long-form audio, then speech recognition accuracy improves, but computational cost increases and system complexity increases

Engineering Contradiction:
Improvespeech recognition accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments long-form audio into multiple shorter segments (e.g., 10-second windows with overlap), processes each segment independently through the ASR model, and then stitches the results together. This segmentation allows the system to handle long-form audio using a simpler model trained on short utterances, resolving the contradiction between accuracy for long audio and system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges short-segment hypotheses into a consolidated hypothesis using a stitching mechanism that aligns and combines the segmented transcriptions. This merging process reconstructs the full long-form transcription from multiple short segments, achieving accurate long-form recognition without requiring a complex end-to-end model.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If end-to-end ASR systems process long-form audio, then speech recognition accuracy improves, but computational cost increases

Engineering Contradiction:
Improvespeech recognition accuracyVSAvoidcomputational cost
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

By segmenting long audio into shorter segments, the system can use a simpler, more efficient ASR model trained on short utterances rather than requiring a complex end-to-end model. This segmentation approach reduces computational cost per processing step while maintaining overall accuracy through the stitching mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system processes only the necessary portions of audio (short segments) at a time rather than processing the entire long-form audio continuously. This partial processing approach reduces computational cost while the stitching mechanism ensures complete and accurate transcription is achieved through combining the partial results.

Inventive Principle:
Principle #16Partial or excessive action

3Device complexity

If audio is segmented into short segments for ASR processing, then computational cost decreases, but speech recognition accuracy for long-form audio deteriorates

Engineering Contradiction:
Improvecomputational costVSAvoidspeech recognition accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent merges short-segment hypotheses into a consolidated hypothesis using alignment-based or serialized stitching methods. This merging process combines the transcriptions from multiple short segments into a coherent long-form transcription, restoring speech recognition accuracy that would otherwise be lost due to the segmentation itself.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The stitching mechanism incorporates feedback loops that align and verify the segmented hypotheses against each other, using overlap regions to ensure consistency. This feedback process corrects potential inaccuracies introduced by segmentation and maintains high speech recognition accuracy in the final consolidated output.

Inventive Principle:
Principle #23Feedback

Data Source

PatentUS12394420B2Hypothesis stitcher for speech recognition of long-form audio
Publication Date: 2025.08.19 MICROSOFT TECHNOLOGY LICENSING LLC
  • US12394420B2 patent drawing
  • US12394420B2 patent drawing
  • US12394420B2 patent drawing

AI summary

A hypothesis stitcher for speech recognition of long-form audio provides superior performance, such as higher accuracy and reduced computational cost. An example disclosed operation includes: segmenting the audio stream into a plurality of audio segments; identifying a plurality of speakers within each of the plurality of audio segments; performing automatic speech recognition (ASR) on each of the plurality of audio segments to generate a plurality of short-segment hypotheses; merging at least a portion of the short-segment hypotheses into a first merged hypothesis set; inserting stitching symbols into the first merged hypothesis set, the stitching symbols including a window change (WC) symbol; and consolidating, with a network-based hypothesis stitcher, the first merged hypothesis set into a first consolidated hypothesis. Multiple variations are disclosed, including alignment-based stitchers and serialized stitchers, which may operate as speaker-specific stitchers or multi-speaker stitchers, and may further support multiple options for differing hypothesis configurations.