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Over-the-air (OTA) Attack Accuracy (Table 5)

Environment

• We utilize the following ASRs
  • Amazon Alexa - Amazon Echo Dot (3rd Gen)
  • Google Assistant - Google Pixel 4
  • Microsoft Cortana - Lenovo ThinkPad X1 Carbon
• Perform experiments under different environments
  • Household (noise: 15-20 dB) – ASR on a table, Logitech Z200 speaker plays adversarial audio
  • Teleconference (noise ≈ Household) – ASR is beside the victim’s laptop, and the laptop plays adversarial audio
  • Vehicle (noise: 60 dB) – ASR (Android Auto / Alexa Auto) is near center console, adversarial audio is played via car speaker (Kenwood KFC-1666S)
• Select 6 commands for each environment (i.e., total 6 * 3 = 18 commands)
  • Two short, two medium and two long commands
• For each of 3 wake-up words (i.e., Okay Google, Alexa, and Hey Cortana), test 18 commands against the corresponding ASR

Experiment Procedure

• Construct 3 wake-up adversary audio files.
  • Adversarial Wake-up Word
• For each command, we perform 10 trials of attacks with the adversarial audio (i.e., 18x3x10=540 trials). An adversarial command may generate multiple adversarial audio files with different playback speeds.
• Adversarial Command: Household
• Adversarial Command: Teleconference
• Adversarial Command: Vehicle
• Derive success rate = number of successful attacks / total number of trials

Result

• Table 5 in the paper depicts overall performance of OTA attacks