Real-Time Neural Voice Camouflage

Columbia University
In Submission

Automatic speech recognition systems have created exciting possibilities for applications, however they also enable opportunities for systematic eavesdropping. We propose a method to camouflage a person’s voice over-the-air from these systems without inconveniencing the conversation between people in the room. Standard adversarial attacks are not effective in real-time streaming situations because the characteristics of the signal will have changed by the time the attack is executed. We introduce predictive attacks, which achieve real-time performance by forecasting the attack that will be the most effective in the future. Under real-time constraints, our method jams the established speech recognition system Deep-Speech 4.17x more than baselines as measured through word error rate, and 7.27x more as measured through character error rate. We furthermore demonstrate our approach is practically effective in realistic environments over physical distances.

Prediction for Real-Time

Streaming audio is a particularly demanding domain to disrupt because the calculation needs to be performed in real-time. By the time a sound is computed, time will have passed and the streaming signal will have changed, making standard generative methods obsolete. The sampling rate of audio is at least 16 kHz, meaning the corruption for a given input must be estimated and played over a speaker within milliseconds, which is currently infeasible. Additionally, when attacks are played over-the-air, the attack needs to be loud enough to disrupt any rogue microphone that could be far away. The attack sound needs to carry the same distance as the voice.

We introduce predictive attacks, which are able to disrupt any word that automatic speech recognition models are trained to transcribe. Our approach achieves real-time performance by forecasting an attack on the future of the signal, conditioned on two seconds of input speech. Our attack is opti- mized to have a volume similar to normal background noise, allowing people in a room to converse naturally and without monitoring from an automatic speech recognition system.

Results

Audio samples

The sound is the original input voice with the attack overlaid, and the image shows the transcription of the attacked input.

Code and models


GitHub

Paper


PDF
@InProceedings{--,
    title={Real-Time Neural Voice Camouflage},
    author={Chiquier, Mia and Mao, Chengzhi and Vondrick, Carl},
    journal={---},
    year={2021}
}			
Acknowledgements

We thank Oscar Chang, Dídac Suris Coll-Vinent, Dave Epstein, Basile Van Hoorick, Purva Tendulkar and Jianbo Shi for their helpful feedback. This research is based on work supported by the NSF CRII Award #1850069 and the NSF CAREER Award #2046910. MC is supported by a CAIT Amazon PhD fellowship. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the sponsors.