Thanks! I doubt they just use high frequency attenuation. I'm surprised
Amazon does not just identify the voices of people in the household.
Commands could be customized to the person asking. If an unrecognized
voice shows up (like from a commercial), the Echo could ask the command to
be repeated.

Harold


> https://www.bloomberg.com/news/articles/2018-02-02/here-s-why-alexa-won-t=
-light-up-during-amazon-s-super-bowl-ad
> "The second tactic describes how a commercial itself could transmit an
> inaudible acoustic signal to tell Alexa to ignore its wake word."
>
>
>
>
>
> -----Original Message-----
>>From: Harold Hallikainen <harold@mai.hallikainen.org>
>>Sent: Feb 2, 2018 12:39 PM
>>To: Pic List <piclist@mit.edu>
>>Subject: [EE] Spread Spectrum Audio Watermarking
>>
>>I'm looking at sending some extremely low speed data under audio to
>>identify the audio. The receiver would be an Android device with internal
>>microphone. I'm thinking of using direct sequence spread spectrum with
>> the
>>level being substantially below the audio so it would appear to be very
>>low level noise. But, my experience with spread spectrum is extremely
>>limited. I'd appreciate any pointers to information on it, especially at
>>audio frequencies, and any open source projects on it.
>>
>>THANKS!
>>
>>Harold
>>
>>
>>
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