The self-expressed goal of this kind of test is to pick a phrase or topic that is so random that it escapes that person's existing ad data profile. As the comment above said, "He doesn't own a swimming pool, doesn't want to, and has never expressed any desire to."

So showing that person an ad for pool fencing is a complete waste; they're never going to click it. If that's what an alleged audio targeting system does, it would make the ad network less profitable than just using the data they already have. So why would anyone build it that way?