The Web Audio API has the ability to extract frequency, waveform, and other data from an audio source, that source is generated at runtime on your device. A firefox developer did a further dive into what the WebAudio based fingerprinting can actually return in firefox. https://developer.mozilla.org/en-US/docs/Web/API/AnalyserNod...

Perhaps accessing the microphone is something else they do, however that is not the issue in my case nor what my article is about.

While it may not be effective at fingerprinting, the side effect of the attempt sure is annoying when it stops my music! Do you know if it would count as a bug if muting the firefox tab or the browser as a whole does not stop the audio stream?

I doubt the FBI will be flying to china to knock down any doors! You aren't wrong though, and countries which enforce GDPR I would expect to make noise if this was happening to their constituents.

Thanks for your input and perspective! Do you think it is a bug that the muting of the firefox tab doesn't stop the audio stream? It is frustrating that companies would use such an annoying tactic to track their users with it also ineffective.

Yes, it is a bug, in fact it's this bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1863193#c9 which is of course getting some more attention now =)

Good to know! I have added a note and link to my post.

I touched on this in my article, once the data has been collected and sent to their servers you have no idea what they do with the information. At least with GDPR it is supposed to be regulated but obviously that is not the case everywhere and websites can still lie.

Does it hold an audio stream open constantly or just briefly during the challenge? On AE it never stops

Just briefly during the challenge.

I use ublock origin and by default it wasn't blocking, i had to make a custom filter to block the scripts in order for it to prevent the audio takeover. Maybe adguard does a better job? Someone else suggested just wholesale disabling of JS but it is the nuclear option.

It just annoyed me so much that it was interrupting my music!

Hell hath no fury like an inconvenienced power user.

The best you can do on the modern web is reduce your fingerprint footprint, though it comes at a cost of websites breaking from JS disabling, or local time zone anonymisation.