Just to clarify, this is not a new finding, but an explainer of a study from 2016.

Note that this fingerprinting technique exploits differences in the behavior of the AudioContext API, but does not (and cannot) actually record audio.

Paper: https://webtransparency.cs.princeton.edu/webcensus/index.htm...

Demonstration (test your own audio fingerprint): https://audiofingerprint.openwpm.com

Discussion from 2016: https://news.ycombinator.com/item?id=11729438

Full list of websites where audio fingerprinting scripts were found (in March 2016): https://webtransparency.cs.princeton.edu/webcensus/audio_fp_...

Source: I'm an author of the research in question (but unaffiliated with this blog).

Note to mods: article title is "Audio Fingerprinting using the AudioContext API". Submitter title is "Sites are using audio (no permissions needed) to track users", which may violate the site guidelines.