Are Our Phones Secretly Listening To Us?

An older iPhone with Siri, Apple’s virtual assistant and chatbot, open.

Most people have probably had an experience that goes something like this: you mention to a friend how you want to go on a vacation and a couple of hours later, YouTube is promoting flight-booking ads to you. Or perhaps, you’ve said that you wanted to start going to the gym routinely, and Instagram shows you workout attire advertisements. After the first couple of times, you’ll start to swear your phone is spying on you. You’re not alone in these thoughts; it is one of the most common technology conspiracies in the modern world. And it makes sense—our cellular devices are equipped with microphones, whose usage we permit, and they are made by companies that are already known for accumulating more user data than necessary.

So, are our phones secretly listening to us? The short answer is probably not. The longer answer is that technology companies don’t necessarily need to. They’ve acquired and synthesized enough information about you to predict your wants without tapping into your microphone, though this doesn’t mean that they don’t use other questionable tactics to learn more about you.

Apple, Google, Facebook, TikTok, and most major apps have all publicly denied listening to user conversations for advertising or any other reasons. Still, people often feel as though their devices are eavesdropping. This is partly due to confirmation bias. You scroll past hundreds of advertisements every day without paying attention. So, if you coincidentally see an ad about shoes after talking to your friend about wanting to buy shoes, your brain connects the two events. The ad most likely would have shown up anyway, but there’s now a reason to remember it.

Researchers have still tried finding truth in this conspiracy theory. In 2018, cybersecurity specialists at a company called Wandera put two phones, a Samsung and an Iphone, in a room and played external cat and dog food advertisements for thirty minutes daily, which they did for three days in a row. They kept open apps like Instagram, Chrome, Facebook, SnapChat, YouTube, and Amazon, granting full permissions to each. Nothing changed. None of the platforms pushed adverts for pet food, and the phones didn’t transmit extra data. Other tests by academic researchers reached the same conclusion: there is no clear evidence that phones secretly record people for personalized advertising.

A graph showing an iPhone’s data usage across different apps (including “Hey Siri”) in a room with no audio vs. a room with audio.

So, if our microphones aren’t being used without our knowledge, why do ads feel so targeted? Companies don’t need to hear your voice when they are familiar with everything else about you. Tech companies already collect information like the websites you visit, the apps you use, your shopping habits, your search history, your location, who your friends are, what you click on, and what you buy. 

Most of the websites and apps on your device may be free to use, but in reality, your data is the price you pay, and it’s quite high. Some apps even track what you do outside of the app! For example, Facebook’s “Like” button, which is on hundreds of thousands of websites, is actually a tracking tool. Meanwhile, Google Analytics, which is installed on millions of websites, collects data on all visitors. Then, we have location apps, which know when you walk into a shopping mall or a restaurant. Even your credit card purchase information can be sold to advertisers through data brokers.

By piecing these clues together, advertisers can foretell products and services you’ll want to indulge in. This technique is called micro-targeting, and it doesn’t require a microphone. It’s purely statistics, algorithms, and a copious amount of personal data.

Even if tech companies aren’t using our phones to secretly record us, the theory isn’t far-fetched. Smart speakers like Amazon’s Alexa and Google Home constantly listen for voice commands, and employees review short audio clips to improve their speech recognition systems. Amazon assures users that Alexa will only send recordings back to the company if it hears “Alexa” or “Echo.” These smart speakers aren’t infallible though, as they often mistake background noise and unclear words as their “wake word.” This results in analysts hearing private information, such as bank information or full names, without the knowledge of the user. The errors that occur aren’t malicious, but they still make people suspicious.

Ultrasonic tracking is another way companies can monitor users. Researchers at the Technical University of Braunschweig in Germany found that some advertising companies experimented with using high-frequency sound waves, inaudible to humans, to link devices together. A commercial could play a hidden ultrasonic tag through a TV, and an app on a nearby phone could receive that sound and log the event. It’s not listening for words, but it is listening for a signal that identifies you for marketing. After the study was published in 2017, Google banned ultrasonic tracking from apps in the Play Store and required all apps to disclose microphone usage.

Modern devices are full of sensors—Bluetooth, GPS, accelerometers, Wi-Fi—and advertisers are always inventing new ways to utilize them. The line between helpful technology and over-surveillance is thinner than we realize. Although these systems don’t secretly listen to us through microphones, they can still create a highly accurate picture of a person’s lifestyle, whether it be where they live or the food they like to eat. If malicious actors access this data, they could attack you through targeted burglary or general stalking.

Concern over phones listening to us is valid, but the actual danger is that companies already know everything about you without ever recording your voice. The worst part is that they collect all of your information legally, through terms and conditions most people never read.