Discrete optimal transport is a strong audio adversarial attack
Abstract
In this paper, we introduce the discrete optimal transport voice conversion (DOT-VC) method. Comparison with NN-VC, SinkVC, and Gaussian optimal transport (MKL) demonstrates stronger domain adaptation abilities of our method. We use the probabilistic nature of optimal transport (OT) and show that DOT-VC is an effective black-box adversarial attack against modern audio anti-spoofing countermeasures (CMs). Our attack operates as a post-processing, distribution-alignment step: frame-level {WavLM} embeddings of generated speech are aligned to an unpaired bona fide pool via entropic OT and a top- barycentric projection, then decoded with a neural vocoder. Ablation analysis indicates that distribution-level alignment is a powerful and stable attack for deployed CMs.
Cite
@article{arxiv.2509.14959,
title = {Discrete optimal transport is a strong audio adversarial attack},
author = {Anton Selitskiy and Akib Shahriyar and Jishnuraj Prakasan},
journal= {arXiv preprint arXiv:2509.14959},
year = {2026}
}