  In this work, we demonstrate the existence of universal adversarial audio
perturbations that cause mis-transcription of audio signals by automatic speech
recognition (ASR) systems. We propose an algorithm to find a single
quasi-imperceptible perturbation, which when added to any arbitrary speech
signal, will most likely fool the victim speech recognition model. Our
experiments demonstrate the application of our proposed technique by crafting
audio-agnostic universal perturbations for the state-of-the-art ASR system --
Mozilla DeepSpeech. Additionally, we show that such perturbations generalize to
a significant extent across models that are not available during training, by
performing a transferability test on a WaveNet based ASR system.
