That said, there's a much easier way to test this. Take two identical voice recognition smart devices (think Amazon Echos), register them each with a new never used Amazon account. Modify one of the devices to have a switch on its mic input which you leave off, and one which you leave on. See if the one with the mic on starts showing ads for things you've never searched for on that Amazon account. If the other one doesn't then there's your answer.
That sounds interesting enough that I might just give it a try.
Given the wide spread of this phenomenon and it’s been a decade, it’s either the most technically complex undetected global conspiracy or it’s not actually real[1].
That said, there's a much easier way to test this. Take two identical voice recognition smart devices (think Amazon Echos), register them each with a new never used Amazon account. Modify one of the devices to have a switch on its mic input which you leave off, and one which you leave on. See if the one with the mic on starts showing ads for things you've never searched for on that Amazon account. If the other one doesn't then there's your answer.
That sounds interesting enough that I might just give it a try.