Multimodal Speech Emotion Recognition and Ambiguity Resolution

Overview

Identifying emotion from speech is a non-trivial task pertaining to the ambiguous definition of emotion itself. In this work, we build light-weight multimodal machine learning models and compare it against the heavier and less interpretable deep learning counterparts. For both types of models, we use hand-crafted features from a given audio signal. Our experiments show that the light-weight models are comparable to the deep learning baselines and even outperform them in some cases, achieving state-of-the-art performance on the IEMOCAP dataset.

The hand-crafted feature vectors obtained are used to train two types of models:

1. ML-based: Logistic Regression, SVMs, Random Forest, eXtreme Gradient Boosting and Multinomial Naive-Bayes.
2. DL-based: Multi-Layer Perceptron, LSTM Classifier

This project was carried as a course project for the course CS 698 - Computational Audio taught by Prof. Richard Mann at the University of Waterloo. For a more detailed explanation, please check the report.

Datasets

The IEMOCAP dataset was used for all the experiments in this work. Please refer to the report for a detailed explanation of pre-processing steps applied to the dataset.

Requirements

All the experiments have been tested using the following libraries:

• xgboost==0.82
• torch==1.0.1.post2
• scikit-learn==0.20.3
• numpy==1.16.2
• jupyter==1.0.0
• pandas==0.24.1
• librosa==0.7.0

To avoid conflicts, it is recommended to setup a new python virtual environment to install these libraries. Once the env is setup, run pip install -r requirements.txt to install the dependencies.

Instructions to run the code

1. Clone this repository by running git clone git@github.com:Demfier/multimodal-speech-emotion-recognition.
2. Go to the root directory of this project by running cd multimodal-speech-emotion-recognition/ in your terminal.
3. Start a jupyter notebook by running jupyter notebook from the root of this project.
4. Run 1_extract_emotion_labels.ipynb to extract labels from transriptions and compile other required data into a csv.
5. Run 2_build_audio_vectors.ipynb to build vectors from the original wav files and save into a pickle file
6. Run 3_extract_audio_features.ipynb to extract 8-dimensional audio feature vectors for the audio vectors
7. Run 4_prepare_data.ipynb to preprocess and prepare audio + video data for experiments
8. It is recommended to train LSTMClassifier before running any other experiments for easy comparsion with other models later on:

• Change config.py for any of the experiment settings. For instance, if you want to train a speech2emotion classifier, make necessary changes to lstm_classifier/s2e/config.py. Similar procedure follows for training text2emotion (t2e) and text+speech2emotion (combined) classifiers.
• Run python lstm_classifier.py from lstm_classifier/{exp_mode} to train an LSTM classifier for the respective experiment mode (possible values of exp_mode: s2e/t2e/combined)

9. Run 5_audio_classification.ipynb to train ML classifiers for audio
10. Run 5.1_sentence_classification.ipynb to train ML classifiers for text
11. Run 5.2_combined_classification.ipynb to train ML classifiers for audio+text

Note: Make sure to include correct model paths in the notebooks as not everything is relative right now and it needs some refactoring

Results

Accuracy, F-score, Precision and Recall has been reported for the different experiments.

Audio

Models	Accuracy	F1	Precision	Recall
RF	56.0	56.0	57.2	57.3
XGB	55.6	56.0	56.9	56.8
SVM	33.7	15.2	17.4	21.5
MNB	31.3	9.1	19.6	17.2
LR	33.4	14.9	17.8	20.9
MLP	41.0	36.5	42.2	35.9
LSTM	43.6	43.4	53.2	40.6
ARE (4-class)	56.3	-	54.6	-
E1 (4-class)	56.2	45.9	67.6	48.9
E1	56.6	55.7	57.3	57.3

E1: Ensemble (RF + XGB + MLP)

Text

Models	Accuracy	F1	Precision	Recall
RF	62.2	60.8	65.0	62.0
XGB	56.9	55.0	70.3	51.8
SVM	62.1	61.7	62.5	63.5
MNB	61.9	62.1	71.8	58.6
LR	64.2	64.3	69.5	62.3
MLP	60.6	61.5	62.4	63.0
LSTM	63.1	62.5	65.3	62.8
TRE (4-class)	65.5	-	63.5	-
E1 (4-class)	63.1	61.4	67.7	59.0
E2	64.9	66.0	71.4	63.2

E2: Ensemble (RF + XGB + MLP + MNB + LR) E1: Ensemble (RF + XGB + MLP)

Audio + Text

Models	Accuracy	F1	Precision	Recall
RF	65.3	65.8	69.3	65.5
XGB	62.2	63.1	67.9	61.7
SVM	63.4	63.8	63.1	65.6
MNB	60.5	60.3	70.3	57.1
MLP	66.1	68.1	68.0	69.6
LR	63.2	63.7	66.9	62.3
LSTM	64.2	64.7	66.1	65.0
MDRE (4-class)	75.3	-	71.8	-
E1 (4-class)	70.3	67.5	73.2	65.5
E2	70.1	71.8	72.9	71.5

For more details, please refer to the report

Citation

If you find this work useful, please cite:

@article{sahu2019multimodal,
  title={Multimodal Speech Emotion Recognition and Ambiguity Resolution},
  author={Sahu, Gaurav},
  journal={arXiv preprint arXiv:1904.06022},
  year={2019}
}