Researchers Reveal Hidden Audio Techniques Designed To Activate Voice Assistants

A new report examines techniques researchers have used to trigger actions from Apple’s Siri, Amazon’s Alexa, and Google Assistant — techniques that involve sending secret audio instructions which are “undetectable to the human ear.”


Researchers have been working on these techniques for years, as they’ve been able to “hide commands in white noise played over loudspeakers and through YouTube videos to get smart devices to turn on airplane mode or open a website,” and now Berkeley researchers say they can even “embed commands directly into recordings of music or spoken text,” The New York Times reports.

These subliminal techniques are designed to “exploit the gap” between recognizing speech from humans and machines, the Times notes. And while there’s no proof these techniques have advanced to the outside world, there’s also no proof they haven’t. (How do you prove that your smart speaker or voice assistant reacted to a hidden audio message?)

It’s been known that you can use obvious voice commands in non-conventional ways to cause actions on virtual assistants — a South Park episode last year messed with Alexa quite a bit — but using hidden instructions is something else entirely.

Obvious Concerns

The Times points out that no American laws restrict the broadcasting of subliminal messages, and though such messages may be an invasion of privacy, “the law has not extended the concept of privacy to machines.”

Amazon, Google, and Apple all responded to the Times. Google said its Assistant has features that “mitigate undetectable audio commands,” while Apple noted that iOS devices have to be unlocked to use Siri for certain commands. Amazon only said it “has taken steps to ensure its Echo smart speaker is secure,” the Times writes.

It’s worth noting that these assistants should be able to recognize if it’s not their own user’s voice, but researchers have proven that doesn’t seem to matter thus far.

Apple also said its HomePod smart speaker isn’t able to perform certain commands, such as unlocking doors. But the virtual assistants should be able to perform such tasks — and just today, a new blog post from smart lock company August claims that “August Makes Unlocking with Alexa Even Easier.”

Phil Dzikiy

Phil Dzikiy

Phil Dzikiy is the former editor in chief of Security Baron. Before, he has worked as a freelance writer and editor at websites like and along with publications like the Lockport Union Sun & Journal and the Greater Niagara Newspapers. With digital and print experience under his belt, Phil has a passion for all things technology including home security, cyber security, and the smart home. His bachelor's degree in Journalism from the University of Maryland College Park initially landed Phil his first job at the Beaver County Times, which has lead to over 15 years of experience as a journalist.

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