Federated Speech Recognition Model Aggregation

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Solution Overview

Problem

Existing automatic speech recognition (ASR) systems face challenges in preserving user privacy due to the need for large amounts of labelled audio data, which raises privacy concerns and is difficult to obtain, especially with decentralized training approaches that require on-premises data processing.

Innovation Solution

A semi-supervised federated learning method is implemented, where local acoustic model weights are generated on client devices without labelled data and shared with a cloud-based training module. The cloud module updates a global ASR system using both local and labelled data, ensuring that only model updates are shared, thus preserving user privacy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If large amounts of labelled audio data are collected and shared for training ASR systems, then the recognition accuracy and model performance are improved, but user privacy is compromised and data security risks increase

Engineering Contradiction:
Improvespeech recognition accuracyVSAvoidprivacy concerns
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system segments the training process into local and global phases. Local models are trained independently on user devices using unlabelled data, while only model weight updates (not raw data) are transmitted to the central server for aggregation. This segmentation allows the system to achieve high recognition accuracy through distributed training while preserving user privacy by keeping sensitive audio data localized.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where local acoustic model weights serve as intermediaries between user data and the global model. Instead of sharing raw audio data, the system exchanges processed model parameters that capture linguistic patterns without exposing sensitive information. This intermediary approach enables knowledge transfer while maintaining privacy boundaries.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If human-labelled data is used for training, then the quality and accuracy of the ASR system is improved, but the cost, time consumption, and labor requirements increase significantly

Engineering Contradiction:
Improvedata qualityVSAvoidtraining efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary training actions at the local level using unlabelled data before global aggregation. Local models are pre-trained on device-specific unlabelled audio data, capturing user-specific acoustic characteristics. This preliminary action reduces the need for extensive human labelling of every dataset, as the federated aggregation process combines these pre-trained local models to build the global model.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system enables self-service training where local devices automatically train their own acoustic models using available unlabelled data without requiring manual intervention for data collection or labelling. The federated learning framework automatically aggregates these self-trained local models, eliminating the need for centralized data annotation teams and significantly reducing labor costs and training time.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If decentralized training is implemented to preserve privacy, then user data security is improved, but the complexity of the training system and coordination overhead increase

Engineering Contradiction:
Improvedata securityVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the advantages of decentralized local training with centralized model aggregation. Local models are trained independently on user devices, preserving data security, while the central server periodically aggregates these local models to update the global model. This merging approach maintains simple client-side implementations while achieving coordinated system-wide learning through periodic server-side aggregation.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentUS12217741B2Large scale privacy-preserving speech recognition system using federated learning
Publication Date: 2025.02.04 CISCO TECHNOLOGY INC
  • US12217741B2 patent drawing
  • US12217741B2 patent drawing
  • US12217741B2 patent drawing

AI summary

A method for implementing a privacy-preserving automatic speech recognition system using federated learning. The method includes receiving, from respective client devices, at a cloud server, local acoustic model weights for a neural network-based acoustic model of a local automatic speech recognition system running on the respective client devices, wherein the local acoustic model weights are generated at the respective client devices without labelled data, updating a global automatic speech recognition system based on (a) the local acoustic model weights received from the respective client devices and (b) global acoustic model weights of the global automatic speech recognition system derived from labelled data to obtain an updated global automatic speech recognition system, and sending the updated global automatic speech recognition system to the respective client devices to operate as a new local automatic speech recognition system.