Photo Credit: iStock A hidden tracking practice on AliExpress appears to have surfaced because of an odd headphone problem, revealing a form of browser fingerprinting most shoppers would likely never notice. In some cases, visiting the site may have set off inaudible audio processing that examined a device instead of merely showing the storefront. The outlet noted that Callaghan was using multipoint Bluetooth headphones linked to his phone while browsing on his computer. According to Ars Technica, the scripts used an oscillator to evaluate Sawtooth waves, a common kind of digital audio output, while keeping the gain at zero so users would hear nothing. Even without audible sound, the browser still processed the audio path and returned the resulting data to AliExpress.