Your Phone Might Be Listening. What We Know And How To Protect Your Privacy.

Your phone can listen for more than speech. An app with microphone access can recognize a coded sound embedded in a television advert and help link that viewing to your device. The US Federal Trade Commission warned app developers about this capability in 2016 [1].

That makes the privacy concern real, but it does not establish that your own phone is doing it. Understanding the mechanism helps separate a documented tracking technique from a claim about every device.

How sound becomes a tracking tool

Research describes tones around 18–20 kilohertz, near the upper limit of human hearing. A compatible app decodes a marker identifying an advert or location. The marker lets software associate the phone with that exposure; recording a conversation is unnecessary. Some people can hear these high frequencies [2].

The FTC’s warning concerned 12 developers whose apps contained Silverpush software without adequate disclosure. It also recorded Silverpush’s statement that its service was not then operating in the United States [1].

A 2017 study found Silverpush functionality in 234 Android apps, but detected no such beacons in television streams sampled across seven countries. These findings document a capability and its limits. They cannot establish its prevalence today [2].

The useful point for phone owners is the receiving app. The US National Institute of Standards and Technology recommends examining microphone requests and blocking access or disabling an app outside its intended use [3].

How to protect your privacy now

1. On iPhone, remove unnecessary access. Open Settings → Privacy & Security → Microphone. Turn off access for apps that do not need it. Apple’s orange indicator shows microphone use without the camera; it does not explain why an app is listening [4].

2. On Android, check each app. Open Settings → Apps → select an app → Permissions → Microphone → Don’t allow. Google’s instructions explain how to change these permissions [5].

3. Review when apps listened. On iPhone, enable Settings → Privacy & Security → App Privacy Report. Apple says it records sensor access after activation and shows the past seven days [6]. On supported Android versions, open Settings → Security & Privacy or Privacy → Privacy dashboard → Microphone to review access and adjust permissions [7].

4. Act on unexplained access. If microphone use does not match an app’s purpose, revoke its permission or disable it, consistent with NIST guidance [3]. An activity log shows access, not proof of ultrasonic tracking. Their purpose here is to restrict which apps can listen through the microphone.

Sources: [1] FTC, 17 March 2016 · [2] Arp et al., 2017 · [3] NIST · [4] Apple permissions · [5] Android permissions · [6] Apple, 19 December 2025 · [7] Android privacy dashboard. Guidance accessed 13 November 2026.