I just Googled "rutabagas" and didn't even get any ads. That doesn't prove that they're not listening to you, only that there aren't any companies buying ads to sell you rutabagas. Same with "alpaca undercoat brushes" - There's a few places that sell various products for grooming but not a single one called an "Alpaca undercoat brush" (most of the results did not include the word undercoat at all).
Now, try to do the same thing with a product that exists and would be advertised, but that you have not searched and would not normally be indicated as something you're interested in.
So, I used to buy into this, but I'm not so sure any more.
For example, the first time Facebook got creepy, I was at an event at the county fairgrounds. There was a company there that was selling, for lack of a better description, prosumer sawmill equipment. They were demonstrating said equipment, and I stood there and watched for a while. Later that day, I see ads for the company that makes said equipment. Now, that's easy enough to do by looking at my location and seeing that other people searched for that company from that location in numbers significant enough to trigger that ad being fed to others in the same location. No audio necessary.
But then, there was the time where we were at my in-laws' and my older son was having fun on their play set and we started talking about buying a play set on the way home, and before we even got home, my wife was looking at Facebook and got ads for play sets. Now, Facebook knows that we're married and have kids of the right age for play sets, but the timing was highly suspect. We hadn't gotten any other ads for play sets before that, our in-laws' set was old enough that it came with the house and so they hadn't searched for nor purchased one. Like I said, we fit the demographic, but the timing was VERY suspicious.
Then, my wife was talking about a very specific medical issue she had just started experiencing, and we got ads for doctors that specialized in that very specific issue. Again, she hadn't searched for anything about it. This time, I have no other explanation than "they were listening". And we've had 4-5 instances like that, where despite all of my technical knowledge and paying attention to this sort of thing, I have no other explanation.
I know there's an awful lot of CPU and network overhead involved, but it doesn't have to be continuous audio. All of the various devices are constantly listening for their keywords (Hey Siri, Alexa, Hey Google), all of them have the capability of changing to other keywords so we know they can listen for several. They could also be listening for a handful of additional keywords like "buy" or "have you heard" that could indicate potential interest in a purchase and trigger maybe a 10-second clip to be sent to a server that would determine if there was potentially a targeted ad that could be sent back to you.
www.yahoo.com
