Press Release Security Smartphones/Mobile Applications

Yes, Your Phone is Eavesdropping on You – and Most Americans Don’t Know How to Stop It

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Study by NordVPN reveals majority of American consumers in the dark on sonic snooping by devices

Half of Americans (53%) say they have seen an ad for a product or service pop up on their phones soon after talking about it or watching it on TV, new research by cybersecurity company NordVPN reveals.

Two in four (50%) consumers admit they have no idea how to prevent this from happening and one in ten (10%) who noticed the adverts said it scared them.

Rather than devices reading your mind, this personalised product placement is due to a type of data monitoring called ultrasonic cross-device tracking. This is where apps on your smartphone listen in to background noise — including conversations — to gather more information about you.

“Later, they share this data across other devices,” says Adrianus Warmenhoven, a cybersecurity advisor at NordVPN.

Smartphones were by far the most common place to find these tailored ads. Four in five (77%) Americans who recognised the phenomenon first spotted it on their handset, with half (52%) seeing it on their computer and a fourth (39%) on their tablet.

Information showing people’s behaviour across devices is extremely valuable to companies, but this type of tracking is controversial because of its lack of transparency and security concerns around consumers’ data.

A key part of cross-device tracking is the use of audio beacons, which are embedded into ultrasound — frequencies above the level that can be heard by humans — and can connect with the microphone on our devices without us knowing. This is one reason many apps ask for permission to access your smartphone’s microphone, even if they don’t involve using your voice.

“While it’s impossible to stop the ultrasonic beacons working, you can reduce the chance of your smartphone listening for them by simply restricting unnecessary permissions you have granted to the apps on your device,” says Warmenhoven.

Ultrasonic Cross-device Tracking — How Does It Work?

Ultrasonic cross-device tracking is used as a method to link all the devices you own to track your behavior and location. These ultrasonic audio beacons can be embedded in many things we interact with daily: TV shows, online videos or websites, or apps on our phones.

Imagine you are watching TV and you see chocolate being advertised. You pick up your phone, and the same chocolate ad appears on your screen. By using ultrasounds, audio beacons can detect when your phone is nearby, and apps on your phone can listen for approximate audio beacons to track what you are doing.

How Can You Reduce Cross-device Tracking?

NordVPN cybersecurity advisor Adrianus Warmenhoven has some top tips to keep snooping devices at bay:

  • Change app permissions. The apps on your smartphone may have some permissions that are not required. For instance, why would a photo-editing app need access to your microphone? If apps on your phone have such non-required permissions, you should revoke these permissions. Apple now requires apps to ask your permission before tracking you or your iPhone across websites or apps owned by other companies, and you can turn this off for all apps. All changes to app permissions can usually be done in the privacy settings on your device.
  • Use a private browser. If you want to keep yourself from tracking, it is best to use a private browser like Tor or DuckDuckGo rather than the incognito mode in Google Chrome. These browsers do not profile you or save any of your personal data for sharing with marketers.
  • Use a VPN. One of the best ways to protect yourself from being tracked is by using a VPN. A VPN is a tool that encrypts every bit of information about your internet activity. It also stops IP-based tracking because it masks your IP address.

About the author



NordVPN is the world’s most advanced VPN service provider, used by millions of internet users worldwide. NordVPN provides double VPN encryption and Onion Over VPN and guarantees privacy with zero tracking. One of the key features of the product is Threat Protection, which blocks malicious websites, malware, trackers, and ads. NordVPN is very user friendly, offers one of the best prices on the market, and has over 5,000 servers in 60 countries worldwide. For more information: