Explaining deep learning models for spoofing and deepfake detection with SHapley Additive exPlanations

Authors: Wanying Ge, Jose Patino, Massimiliano Todisco, Nicholas Evans

Published: 2021-10-07 10:00:04+00:00

AI Summary

This paper uses SHapley Additive exPlanations (SHAP) to analyze deep learning models for spoofing and deepfake detection. It reveals unexpected classifier behavior, identifies key contributing artifacts, and highlights differences between competing models, promoting explainable AI in this field.

Abstract

Substantial progress in spoofing and deepfake detection has been made in recent years. Nonetheless, the community has yet to make notable inroads in providing an explanation for how a classifier produces its output. The dominance of black box spoofing detection solutions is at further odds with the drive toward trustworthy, explainable artificial intelligence. This paper describes our use of SHapley Additive exPlanations (SHAP) to gain new insights in spoofing detection. We demonstrate use of the tool in revealing unexpected classifier behaviour, the artefacts that contribute most to classifier outputs and differences in the behaviour of competing spoofing detection models. The tool is both efficient and flexible, being readily applicable to a host of different architecture models in addition to related, different applications. All results reported in the paper are reproducible using open-source software.


Key findings
SHAP analysis revealed unexpected reliance on non-speech intervals for some classifiers. It also highlighted the importance of specific frequency bands for distinguishing between bona fide and spoofed speech, and showed differences in how different models focus on temporal segments for classification.
Approach
The authors employ SHAP values to explain the behavior of deep neural network-based spoofing detection systems. They analyze the contribution of each spectro-temporal bin in the input spectrogram to the classifier's output, visualizing these contributions to understand which features drive the model's decisions.
Datasets
ASVspoof 2019 logical access (LA) database
Model(s)
PC-DARTS (partially connected differentiable architecture search) and 2D-Res-TSSDNet models
Author countries
France