'I know this is happening. No one can tell me otherwise. I've experienced it and so have friends."
Dubliner Jeremy Dixon is convinced. Our phones are being secretly used as tools by Facebook and Instagram to record our physical conversations, which are then mined for ads which we see when we open our social apps.
"It happened to me in a pub with mates," the 98FM DJ told me. "We were chatting and an odd topic came up, alpacas. I'd never Googled it or looked it up. The next thing, I start seeing ads for alpaca farms in my feed."
Jeremy is not alone. The theory that Facebook, Google, Amazon and other big online tech companies are secretly listening to our conversations through the microphones on our handsets is rife.
As a technology reporter, it's the most consistent question I've received over the last three years.
"Is my phone spying on me?"
"How on earth can something someone said to me suddenly turn up in my ads?"
"I'm not one for conspiracy theories, but it's just too big a coincidence."
"Let me tell you about the ad I saw after talking to my mam the other day…"
Repeated, explicit denials from Facebook, up to and including its chief executive Mark Zuckerberg, cut no ice. For some, the timing between what we just talked about and the ad we're now suddenly seeing is just too suspicious.
"They're tracking our location and lots of other stuff," says Alan Smeaton, Professor of Computing at Dublin City University. "It's not hard to imagine that they're doing more. Our trust in companies like Facebook is decreasing."
Everyone, from the Irish data protection commissioner to the US Senate to those inside Facebook's Irish office, says that to listen in on us secretly would be unethical and illegal.
But does that actually mean it's not happening?
"Technically, they could do it," says Dublin-based Patricia Scanlon, founder of SoapBox Labs and one of the leading artificial intelligence and voice technology experts in the industry. "I don't think they would reap the economic benefits from the amount it would cost them to do it, technically speaking. But they have the capability to gather snippets throughout the day if they really wanted to."
Hard proof is difficult to find.
So the Irish Independent decided to run a carefully calibrated test with seven of our journalists (including this reporter).
Each journalist was given a script that contained specific trigger words. They then read the script out loud directly in front of their phones, making sure that the 'microphone' setting on their Facebook and Instagram apps was switched on. A week of monitoring their social media ads ensued.
To enhance the test, the trigger words chosen have nothing to do with our test subjects' current lives or online searches.
So a sports-loving male colleague, who would usually see ads for gadgets and cars had a chat about women's handbags and the shops you might buy them in. A magazine editor talked in depth about retirement homes and what services they offer. And so on.
The participants took part on condition that they had not Googled such terms before. Here is an example of such a conversation with Gavin McLoughlin, the Irish Independent's business news editor.
Gavin: Do you know anything about women's handbags?
Adrian: A little bit, yes.
Gavin: Good. I can't make up my mind whether to get a Michael Kors bag or a Versace bag for my girlfriend.
Adrian: Well don't forget Burberry.
Gavin: Burberry? What kind of bags do they have?
Adrian: Leather ones with gold trimming.
Gavin: Right. What about Ralph Lauren? Or Kate Spade?
Adrian: They're pretty good but not as fancy as DKNY.
Gavin: What shops sells these bags?
Adrian: Ah the usual, Debenhams, Accessorize.
Gavin: Boohoo? Good call. I've been meaning to buy something there for a while. I'll try Asos as well.
Adrian: What about yourself? Don't you deserve something, too?
Gavin: You know what, you're right. I've had my eye on a Barbour leather men's bag for a while. I hear you can get them in River Island, too. I also really like Herschel backpacks, too.
And here's one of the other scripted conversations, this time with staff business reporter Ellie Donnelly.
Ellie: I'm feeling bad about eating meat - I'm really thinking about becoming a vegan.
Adrian: Really? How come?
Ellie: I just don't like the idea of eating animals anymore.
Adrian: Is it anything to do with that Greggs campaign?
Ellie: No, but I've seen the same kind of campaigns from McDonald's and Burger King.
Adrian: But where will you actually get lunch?
Ellie: I don't know, does Starbucks do any vegan meals?
Adrian: If you could drink coffee as vegan, yes.
Ellie: I don't suppose I'll be eating in Supermac's anymore then.
Adrian: Aren't you worried about nutrition?
Ellie: No, I can just take vitamin supplements and iron tablets. I think Sona and Wellman do them.
Adrian: Where would you get them?
Ellie: I can get them from McCabes Pharmacy or even Boots.
All of the test conversations used highly actionable, ad-friendly target words, themes and brands. (The other four scripted chats were about fashion, tech, music and care services.)
So did any ads turn up in the test subjects' feeds on foot of the physical conversations?
Actually, yes - twice.
Both occurred within Ellie Donnelly's Instagram feed, where an ad for Boots, one of the brands discussed, appeared. "Give your January a little boost," read the sponsored post on Instagram. Ellie also saw an ad for 'MyProtein', a food supplement company, in the same Instagram feed.
"I don't think I've seen ads in my feed for Boots before," the journalist says. "But I do follow some fitness accounts, so it's not outside the bounds that I might see an ad for MyProtein."
But Ellie saw no related ads for veganism or diets, despite several big marketing pushes this month around the topics.
As for the other five test participants, no ads that related to anything in the scripted conversations turned up in their respective Facebook or Instagram feeds, nor on 'programmatic' ad feeds. (A 'programmatic' ad is the kind that you notice following you around different websites. They're often triggered by your online behavioural activity.)
So out of six scripted conversations using over 40 bait-words, there was one hit ('Boots') and one possible hit ('MyProtein').
If the phones were listening, that's a terrible return rate for any advertisers that thought they could capitalise.
"I buy Facebook ads," says digital marketing expert Damien Mulley of the Cork-based firm Mulley Communications. "So if this were something that was available as an advertising product, I'd probably be interested. I certainly know that many would want to buy ads if it were real. But I've never seen any way to do it."
Nevertheless, it's still worth asking the question about the one that seemed to appear after it was talked about. Why did an ad for Boots turn up in Ellie's feed within days of mentioning it out loud? Is this proof that Instagram was listening in on the physical conversation?
"I would say that the reason that so many of us are seeing ads in this way is that these companies know so much about our lives," says Patricia Scanlon.
"There's an expression, the creepy valley. This is where companies are trying to hold back on letting you know how much they actually know about you because they fear it will freak you out."
According to Scanlon, services like Facebook, Instagram and Google are very good at guessing what you might be interested in because of location, biographical and interest-based information that you either freely give or allow it to collect.
In Gimlet's excellent 'Reply All' podcast on the topic, an example given was of a man talking to his mother about her favourite perfume being confiscated by airport security as she was flying out to visit him.
Later that day, he saw an ad for the same perfume in his Facebook feed. He had never looked it up online or bought it before. So he became convinced that Facebook had listened in to his phone conversation with his mother. But when they dug deeper, they found that not only were the mother and son Facebook friends, but it was the mother's birthday later that month. Furthermore, Facebook could tell (through location data) that the mother was travelling to meet her son and that the son was picking her up at the airport (a place you often buy perfume as a gift).
It didn't take that clever of an algorithm to guess that a thing he might want to buy was his mother's favourite perfume for her birthday, especially as he was at an airport and his mother was travelling to meet him.
Going back to our own test case, a glance through Ellie's ad feed on Instagram before the test showed ads for fitness clothes, restaurants, alcohol brands, snack foods and interior design.
It's possible, therefore, that Instagram served Ellie an ad for Boots based on her interests, age, gender and location.
I asked Ireland's data protection commissioner, Helen Dixon, whether she is aware of, or investigating, any allegations against Facebook (or Instagram, which Facebook owns) for surreptitiously listening to users through our microphones.
Dixon, who has more than one formal investigation into Facebook under way at present for other reasons, said that there are none.
Some within the ranks of the Irish multinational tech industry believe that the fines and penalties for recording people without their knowledge under Europe's new GDPR data privacy law would see a transgressor come close to be being bankrupted
"That's basically a company-ending thing," says a senior executive in one of the biggest multinational tech firms here. "It would be reckless beyond belief."
Aside from the ethics and politics behind the issue, some experts say that the technical requirements needed to listen to our conversations are simply too hard and expensive to do.
"What would have to happen if Facebook was listening is that all your conversations would have to be streaming to the cloud," says Patricia Scanlon. "When you think of how many people in the world are on Facebook, that is an insane amount of data and an insane amount of processing."
In Ireland, that would mean having an open line on more than 3 million phones. Worldwide, it would be over 2 billion phones, some in countries with expensive data charges.
Aside from the fact that this would likely turn up on our phone's data records (not to mention our monthly phone bills), experts say that it would also mean at least 30 times more internet traffic than Facebook is currently processing.
"Ah," the believer might say, "but what about trigger words to wake the microphone up?"
This is a logical point. In an age of Amazon Alexa, Google Home and Siri, why isn't it reasonable to imagine that Facebook (or Amazon or Google) has a watchlist of trigger words that could wake the microphone up?
"Amazon has filed a patent on this recently, called voice sniffing," says Scanlon. "It's looking for key words rather than just the wake word of 'Alexa'. It wants to start looking for your likes or dislikes. They haven't implemented it yet and they say it's just a future-proofing thing. But it is possible, and a lot of these companies are reserving their right to do it in the future."
In answer to a series of questions from the Irish Independent on the issue, Facebook Ireland flatly denied that any such activity occurs.
"Facebook does not use your phone's microphone to inform ads or to change what you see in your News Feed. Some articles have suggested that we must be listening to people's conversations in order to show them relevant ads. This is not true. We show ads based on people's interests and other profile information, not what you're talking out loud about."
Such a black-and-white denial from Facebook suggests that either it's not happening, it's a conspiracy or it's the worst bug that the company has ever had.
This last 'bug' possibility - that it's something which occurs that they're not entirely aware of - is hard to completely rule out. The last 24 months of Facebook's history, after all, is littered with bugs and breaches where all sorts of personal data has been exposed and compromised.
Each time, the company profusely apologises and says they'll 'fix' it.
This has led to a breakdown in trust between the big social media companies and us, the users.
"We've become way more suspicious of them," says DCU's Professor Smeaton.
"That said, most of us aren't too bothered with Facebook tracking our location or looking in on what we say we like online. Facebook is a free service and that's the Faustian pact we've done. But listening in to our conversations would cross the boundary. It would go too far."
Three ways for Facebook users to cut down on 'familiar' ads following you online:
1 Change your Facebook advert settings
If you're a Facebook user, go into the app's settings and choose 'review your ad preferences'. Turn to 'off' the following options: (a) 'ads based on data from partners', (b) 'ads based on your activity on Facebook Company Products that you see elsewhere' and (c) 'ads that include your social actions'. Now go into 'your information' and turn all of the options ('relationship status', 'employer', 'job title' and 'education') off. Lastly, go into 'your categories', tap on each category and choose 'remove category'.
2 Switch off location-tracking
On your smartphone's settings, go into 'privacy' and turn 'location services' off. Then, still in your phone's 'settings', scroll down to the Facebook app, tap it and turn off 'location'.
3 If using a PC, disallow 'cookies' on your browser
If you're using a laptop or PC to browse online and social media, go into your browser's settings and disable cookies. (Your 'browser' is Safari, Internet Explorer, Chrome or Firefox.) As an extra precaution, try to use 'private' or 'incognito' mode on the browser.
It's important to note that this won't stop ads appearing. But those ads will be slightly more generic than ones based on your Facebook habits or the habits of your Facebook friends.