Ask HN: Is it freqency illusion or is my phone listening? Can we test it?

I have noticed on two occasions that we had a conversation and within 10 minutes, the phone displayed an ad about that conversation. Both ads could be explained by using a mosaic of other factors and just getting lucky that we just had the conversation. In neither case did I search for the topic recently, and in one case, never before:

1) A friend was over and he suggested looking at tungsten wedding rings. I had no interest in tungsten and just listened to him. Never searched. 10 minutes later, my now wife had an add for a tungsten wedding wring. On one hand, I'm sure FB can easily figure out that we were about to get married by our searches, but neither of us had looked at tungsten wedding rings.

2) Last night we were watching an episode of ballers and they mentioned Zika. We had a 2 minute convo about how that was a big deal 12 months ago.

I picked up my phone 5 minutes later and the first ad on Instagram is from the CDC about Zika.

Obviously it could have been listening, or it could have just triangulated the wedding date etc. and served the ad.

I'm curious if there is anyone out there researching this or who can definitively answer whether phones are listening or whether this is just frequency illusion?