Although Alexa may talk to itself at times it is designed not to answer. Filed back in 2014, Amazon patented methods to prevent the device from accidentally waking up while hearing its name called during commercials. Amazon used something called acoustic fingerprint technology, which allowed the echo to differentiate between its owner's voice and that of the respective ad. It appears that Amazon thought of this problem well in advance as the patent was filed even before the Echo was released.
The patent details two methods used to differentiate real vs. ad commands. First, a small snippet of a commercial is delivered to Echo devices prior to air time. The Echo then proceeds to process the sample and then compare the audio to those of the owner's commands to determine if they are real. The second method involves Amazon including an acoustic signal, undetectable by the human ear, in the ad to alert the Echo device that the command is not genuine. This method was backed up by a Reddit user by the name of Asphyhackr who did a bit of their own research. While running Alexa commercials through audio editing software, Asphyhackr unearthed faint trails of sound between 3,000 and 6,000 hertz that could not be ascertained by the human ear. Amazon can also use the technology described in the patent in other ways. Using Amazon Cloud Services, it can detect a massive influx of the same voice using the same command at the same time. Although this is not a perfect science, Amazon boasts this does have an 80-percent to 90-percent success rate.
This technology is beneficial on multiple fronts both for Amazon and Echo device owners. For Amazon, the benefit is clearly for its infrastructure. If hundreds of thousands of Echo devices suddenly queried Amazon Cloud services simultaneously, the strain on its servers would be substantial. Even if Amazon were only able to block the amount that was mentioned, the resulting impact would be mitigated significantly. From an end user's perspective, the benefit is a bit simpler. As more Echo ads are run with the device's popularity increasing, it might tend to frustrate owners to have their units going off every time an ad is played.