Your phone’s microphone constantly listens for ultrasonic beacons—high-frequency sound waves beyond human hearing—that track your movements through stores without your consent. Retailers embed these inaudible signals (18-22 kHz) into their audio systems, creating a hidden surveillance network. When your phone picks up these signals, apps with microphone permissions relay your location and behavior to tracking servers.
This isn’t theoretical. Researchers have confirmed active ultrasonic tracking in European stores. Companies like SilverPush and Lisnr use this method to monitor your path through aisles, link your in-store activity to online behavior, and build detailed profiles by combining data from TV ads, Wi-Fi logins, and other sources.
By 2017, over 230 Android apps were found to include ultrasonic listening capabilities. Despite FTC warnings to developers, the practice continues under the guise of “legitimate” uses like device pairing.
To protect yourself, audit app permissions rigorously. Deny microphone access to shopping, loyalty, and entertainment apps unless absolutely necessary. Unlike simply muting your phone, revoking mic access stops ultrasonic tracking at the source.
As IoT devices expand, this surveillance method may evolve—staying vigilant with permissions remains your best defense against unwanted tracking.
