Speech Spoofing Detection
Stacked Fourier Neural Network for Speech Spoofing Detection
With the advancement of speech synthesis and conversion technologies, highly realistic spoofed speech poses significant threats to forensic authentication, financial security, and content integrity. Although existing end-to-end speech spoofing detection models have achieved progress in time-domain feature modeling, their capability to capture periodic structures in the frequency domain remains limited, constraining their performance on neural vocoder-based and period-enhanced spoofed speech. To address this limitation, this paper introduces Fourier analysis into the end-to-end detection framework and proposes a Stacked Fourier Neural Network (SFNN). The SFNN incorporates learnable Fourier-domain mappings at multiple layers of an end-to-end model, and through a stacking design, progressively enhances the modeling of spectral periodic structures. Multi-position ablation studies demonstrate that introducing SFNN at the front-end feature extraction stage is the most effective. On the ASVspoof 2019 dataset, the model integrated with SFNN reduces the baseline EER from 0.65% to 0.34%, while also exhibiting stronger transferability on external test sets such as ASVspoof 2021. These results indicate that SFNN provides an effective approach to improve the frequency-domain modeling capability of speech spoofing detection systems.
Executive Impact: Stacked Fourier Neural Network for Speech Spoofing Detection
The research introduces the Stacked Fourier Neural Network (SFNN) to enhance speech spoofing detection by explicitly modeling frequency-domain periodic structures. SFNN, through learnable Fourier-domain mappings and a stacking design, significantly improves detection accuracy and generalization across various datasets. Integrating SFNN at the front-end feature extraction stage reduces the Equal Error Rate (EER) from 0.65% to 0.34% on ASVspoof 2019, demonstrating superior performance in identifying advanced synthetic speech.
Deep Analysis & Enterprise Applications
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The core innovation of the SFNN is its ability to explicitly model frequency-domain periodic structures at multiple network layers. Unlike conventional Fourier transforms, SFNN's mappings are parameterized and optimized in a data-driven manner, allowing for adaptive enhancement of representations for periodic anomalies, which are crucial discriminative cues in spoofed speech. This approach leads to a progressive enhancement of features across various hierarchies.
The SFNN constructs frequency-domain mappings as parameterized neural operators, making them adaptively optimizable. Given an input feature x(t), it's transformed into its complex Fourier representation X(f). Then, amplitude A(f) and phase Φ(f) are extracted, capturing high-frequency noise and periodic discontinuities. These are processed by a multilayer perceptron (gMLP) for learnable mapping. A spectral modulation mechanism with learnable scaling factors a and β controls the enhancement, and the modulated features are finally reconstructed back to the time domain.
Ablation studies confirm that introducing SFNN at the front-end feature extraction stage yields the most significant performance improvements, reducing the baseline EER from 0.65% to 0.34% on ASVspoof 2019 LA. The stacking design, with two layers, proves optimal for refining multi-scale periodic features, indicating a balance between representational power and generalization. The model also shows stronger transferability to external datasets like ASVspoof 2021.
The SFNN's enhanced capability to detect highly realistic spoofed speech provides substantial enterprise value, particularly in sectors reliant on voice authentication (e.g., finance, customer service, national security). By improving robustness and generalization, it protects against evolving threats from advanced speech synthesis and conversion technologies. The method's effectiveness on both ASVspoof 2019 and 2021 datasets demonstrates its readiness for real-world deployment in diverse and challenging scenarios.
The Stacked Fourier Neural Network (SFNN) addresses the limitation of existing end-to-end models in capturing periodic structures of spoofed speech. By introducing learnable Fourier-domain mappings and a stacking design, SFNN progressively enhances the modeling of spectral periodic structures, significantly improving detection capability for highly realistic synthetic speech.
Enterprise Process Flow
| Model | SFNN | 19LA EER (%) | 21LA EER (%) | 21DF EER (%) | ITW EER (%) |
|---|---|---|---|---|---|
| AASIST | no | 0.65 | 8.49 | 5.25 | 16.75 |
| AASIST | yes | 0.34 | 5.21 | 5.47 | 11.47 |
| RawNet2Spoof | no | 4.13 | 12.34 | 6.92 | 20.55 |
| RawNet2Spoof | yes | 4.24 | 12.01 | 6.85 | 20.14 |
Enhancing Enterprise Security with Advanced Spoofing Detection
Problem: Traditional voice authentication systems are increasingly vulnerable to sophisticated AI-generated spoofed speech, posing significant threats to financial security and forensic integrity. Existing detection methods often struggle with generalization to unseen attacks and complex acoustic conditions.
Solution: Our SFNN-integrated models provide a robust solution by explicitly modeling frequency-domain periodic structures, which are key discriminators for synthetic speech. This allows for superior detection accuracy and improved transferability to novel spoofing methods, safeguarding critical voice-based interactions.
Outcome: Enterprises can expect significantly reduced fraud rates due to advanced spoofing, with EERs decreasing from 0.65% to 0.34% on relevant benchmarks. This translates to enhanced security, improved trust in voice authentication, and a more resilient defense against evolving AI-driven threats.
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