RoVo: Robust Voice Protection Against Unauthorized Speech Synthesis with Embedding-Level Perturbations

TL;DR

RoVo is a proactive defense method that injects adversarial perturbations into embedding vectors of audio to protect against speech synthesis attacks and remains effective against speech enhancement techniques.

Contribution

It introduces embedding-level perturbations for robust voice protection, outperforming existing methods and resisting secondary speech enhancement attacks.

Findings

Increased Defense Success Rate (DSR) by over 70% against state-of-the-art models

Achieved 99.5% DSR on commercial speaker-verification API

Perturbations remain effective under strong speech enhancement conditions

Abstract

With the advancement of AI-based speech synthesis technologies such as Deep Voice, there is an increasing risk of voice spoofing attacks, including voice phishing and fake news, through unauthorized use of others' voices. Existing defenses that inject adversarial perturbations directly into audio signals have limited effectiveness, as these perturbations can easily be neutralized by speech enhancement methods. To overcome this limitation, we propose RoVo (Robust Voice), a novel proactive defense technique that injects adversarial perturbations into high-dimensional embedding vectors of audio signals, reconstructing them into protected speech. This approach effectively defends against speech synthesis attacks and also provides strong resistance to speech enhancement models, which represent a secondary attack threat. In extensive experiments, RoVo increased the Defense Success Rate (DSR) by over 70% compared to unprotected speech, across four state-of-the-art speech synthesis models. Specifically, RoVo achieved a DSR of 99.5% on a commercial speaker-verification API, effectively neutralizing speech synthesis attack. Moreover, RoVo's perturbations remained robust even under strong speech enhancement conditions, outperforming traditional methods. A user study confirmed that RoVo preserves both naturalness and usability of protected speech, highlighting its effectiveness in complex and evolving threat scenarios.