The honest answer
Researchers who have gone looking for it haven’t found it. In 2018, Northeastern University researchers ran more than 17,000 Android apps through automated testing specifically looking for hidden audio recording. They found none — “there were no audio leaks at all — not a single app activated the microphone” — while confirming that some apps were secretly taking screenshots and screen recordings without telling users (Northeastern Global News). No study can prove a universal negative — it tested a large sample of Android apps, not every app, platform, or device — but the researchers went looking for microphone spying and caught a different privacy problem instead.
The theory got a fresh, real-world test in 2026. Cox Media Group, an ad firm, had spent a couple of years pitching a product called “Active Listening,” claiming to capture “real-time intent data” from smart devices and turn overheard conversations into ad targeting. In May 2026, the FTC announced proposed settlements with Cox Media Group and two smaller marketing firms totaling nearly $1 million, finding the product never listened to anyone: “this service did not, in fact, listen in on consumers’ conversations or use voice data at all” — what customers were actually buying was a marked-up list of emails from data brokers (FTC press release). The companies agreed to settle; the orders are proposed and open to public comment before becoming final. The FTC also noted that even if the listening claim had been true, burying consent in an app’s terms of service wouldn’t count as valid opt-in for that kind of data.
So why do the ads feel so accurate
Because the profiling doesn’t need your microphone. Advertisers routinely link multiple devices to the same person or household without any audio at all: the FTC’s staff report on cross-device tracking describes how ad platforms infer that devices sharing a public IP address — like a phone and a computer on the same home Wi-Fi — belong to the same household, then carry an ad seen on one device over to another (FTC Cross-Device Tracking report). Search and browsing history do similar work: talking about a product often coincides with searching for it, and that is tracked, extensively, through your advertising ID. Advertisers also build “lookalike audiences” — Meta’s own help pages describe uploading a list of existing customers so the ad platform can find other people who share similar demographics, interests, and behaviors (Meta Business Help Center); shared habits in a household or friend group can sweep you into one with no one having said a word.
None of that requires audio. It only needs to feel like it did, which is a much lower bar — the coincidence of thought-then-ad is common enough to be a shared experience, even when the mechanism is entirely different. Learn more about the identifier behind most of this on Advertising IDs.
When a microphone genuinely is in use
This is the part worth being precise about, because “no evidence phones secretly record for ads” is not the same as “microphones are never used.”
Voice assistants record on purpose, and keep some of it. If you use Siri, Apple can store and have employees review a sample of your Siri, Dictation, and Translate audio if you’ve opted into “Improve Siri and Dictation” — tied to a rotating device identifier, not your Apple Account, retained for up to two years, with a smaller reviewed subset kept longer (Apple’s Improve Siri and Dictation privacy page). Delete on-device history from Settings → Siri → Siri & Dictation History, and manage the setting at Settings → Privacy & Security → Analytics & Improvements (Apple). Google’s equivalent, voice and audio activity with Google Assistant, is only saved to your account if you turn it on under Web & App Activity — off by default (Google Help).
Apps with microphone permission can use it while you’re using them — that’s the point of a voice memo app, a video call, or a karaoke game. The Northeastern researchers weren’t claiming microphones are never accessed; they found zero evidence of the specific, secret, background-recording-for-ads scenario people fear (Northeastern Global News).
How to check for yourself
Both major phone platforms show you, in real time, when a microphone or camera is active — make checking a habit, not a one-time thing.
On iPhone: an orange dot (orange square if Differentiate Without Color is on) means an app is using the microphone; a green dot means the camera alone, or the camera and microphone together (Apple Support). Pull down Control Center to see which app it was. To revoke access outright: Settings → Privacy & Security → Microphone (or Camera), then toggle it off per app (Apple Support).
On Android: recent Android versions display a status-bar indicator whenever an app is actively using the camera or microphone, which you can tap to see which app it was (Android Open Source Project). From Settings → Security & Privacy → Privacy → Privacy dashboard, you can see which apps have accessed the camera, microphone, and other sensors over roughly the past day or week depending on your Android version, then manage each app’s access from there — menus vary by phone maker (Google Android Help).
A quiet indicator light is a good sign, not a guarantee — see What a scan can and can’t tell you for why no single check can promise a device is clean.
The real distinction: adtech versus a person
Everything above is about commercial ad targeting, which the evidence says doesn’t rely on secret audio capture. That is a different question from whether a specific person — an abusive partner, an ex, a family member — has installed something on your phone that genuinely can record you.
That’s not a myth. Consumer-grade stalkerware exists, is sold despite platform bans, and some products are built to capture audio, calls, and surroundings. What should make you suspect a person rather than an ad network is behavioral, not physical: someone who knows things they shouldn’t, repeats back private conversations, or shows up somewhere you only mentioned out loud. Is someone tracking my phone? walks through those signals and how to tell which situation you’re in. If you believe someone is currently tracking you, read Safety first: before you remove anything before changing any settings — the wrong move at the wrong time can alert the person watching.