Speech Emotion Recognition via CNN-LSTM Self-Attention

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Solution Overview

Problem

Conventional spoken dialog systems fail to appropriately handle human emotion, resulting in a cold or robotic impression, and existing speech emotion recognition technologies struggle to focus on features in periods remarkably associated with emotion in an utterance.

Innovation Solution

An end-to-end neural network-based information processing apparatus and method that extracts local features from speech data, encodes chronological features, generates weighted features at specific points in time associated with emotion, and classifies emotions using a CNN-BLSTM with self-attention mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional machine learning methods (HMM, SVM) are used for speech emotion recognition, then the system structure is simpler, but the emotion recognition accuracy is lower

Engineering Contradiction:
Improveemotion recognition accuracyVSAvoidsystem structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional machine learning methods (HMM, SVM) with deep learning neural networks (CNN, LSTM). This substitution transitions from traditional mechanical/mathematical processing to neural network-based processing, achieving higher emotion recognition accuracy while accepting increased system complexity. The CNN-LSTM architecture specifically substitutes previous methods to capture both spatial and temporal features in speech data.

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

Solution Approach 2:

The patent employs a composite neural network architecture combining CNN and LSTM layers. The CNN component extracts local spectral features while the LSTM component captures temporal dependencies. This composite structure integrates the strengths of both network types to achieve superior emotion recognition performance compared to using either method alone.

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If the entire speech utterance is processed for emotion recognition, then all available data is utilized, but the system cannot focus on emotion-critical periods

Engineering Contradiction:
Improveemotion detection precisionVSAvoidemotion-critical feature loss
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent applies local quality by enabling different parts of the speech signal to be processed with different importance weights. The attention mechanism identifies and emphasizes local regions containing emotion-critical information while suppressing less relevant segments. This allows the system to focus computational resources on emotionally significant portions of the utterance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The attention mechanism serves as an intermediary between the LSTM output and the final classification layer. It selectively weights different time steps in the sequence, acting as a mediator that determines which portions of the processed speech signal should contribute most to the emotion classification decision.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If manual feature extraction (LLD) is used, then the feature selection process is interpretable, but the emotion recognition accuracy is limited

Engineering Contradiction:
Improveemotion recognition accuracyVSAvoidfeature extraction complexity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces manual low-level descriptor (LLD) feature extraction with automatic deep learning-based feature learning. The CNN layers automatically learn and extract relevant spectral features from raw speech spectrograms, eliminating the need for manual feature engineering. This substitution achieves superior accuracy while increasing computational complexity.

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

Solution Approach 2:

The neural network performs self-service by automatically learning optimal feature representations from the input speech data without human intervention. The CNN architecture autonomously identifies and extracts discriminative features during training, replacing the manual feature extraction process that previously required expert knowledge and manual tuning.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS11443759B2Information processing apparatus, information processing method, and storage medium
Publication Date: 2022.09.13 HONDA MOTOR CO LTD
  • US11443759B2 patent drawing
  • US11443759B2 patent drawing
  • US11443759B2 patent drawing

AI summary

An information processing apparatus includes a memory storing instructions. The instructions cause the apparatus to extract a plurality of local features from data indicating a speech, the characteristics of feature extraction being formed through learning; and to encode a series of chronological features of the data based on the plurality of local features, characteristics of encoding the series of chronological features being formed through learning. The instructions also cause the apparatus to generate information obtained by weighting features at a specific point in time associated with emotion classification, of the series of chronological features encoded, characteristics of weighting the features at the specific point in time being formed through learning; and to classify emotion corresponding to the data using the information obtained by weighting the features at the specific point in time, characteristics of classification being formed through learning.