Amazon tricks Echo devices into ignoring wake-up words

Amazon tricks Echo devices into ignoring wake-up words
Amazon purchased a commercial airtime to promote its Echo devices during the Super Bowl this year. However, Echo owners didn’t see their devices being activated during the 90-second advertisement in which the command “Alexa, what’s the weather like today?” was spoken.

According to Amazon, the company has altered the Alexa advertisement so that Echo devices in users’ homes won’t be activated. This technique caught people’s attention since it made advertising Echo possible without annoying the device owners.

Back in September 2014, Amazon applied a patent named “audible command filtering,” which prevents the voice assistant from being awakened during a broadcast watched by a large population.

Two techniques are used in the patent. The first is to transmit a snippet of a commercial to Echo devices before it presents to audiences. The Echo can then compare live commands to the acoustic fingerprint of the snippet to check whether the commands are truly made by its owners.

The second technique is that the commercial needs to transmit an inaudible acoustic signal to tell Alexa to ignore this wake-up word. After importing the audio file into editing software and adjusting the audio to the 3,000Hz to 6,000Hz spectrum range, the Alexa system will ignore commands in the spectrum. That’s why this Super Bowl ad didn’t wake up thousands of Echo devices during the game.

What if a talk show or other unexpected events mention Alexa? According to Amazon, its acoustic fingerprints on-the-fly system will solve this problem. When multiple devices start waking up simultaneously during a broadcast event, similar audio will be streaming to the AWS cloud and its algorithm will match the audio from distinct devices, preventing more Echo devices from responding.

The system isn’t perfect for unexpected events, but Amazon says it can stop 80 to 90 percent of devices from responding.

Meanwhile, Google Home owners were annoyed by a nationwide Burger King commercial in which the sentence “Ok Google, what is the whopper burger?” was spoken. It ended up triggering thousands of Google Homes to answer the question in each user’s home.

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