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“Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

arstechnica.com

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Re: “Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

#11

Post by mSparks »

iotscale wrote: post #7
mSparks wrote: post #6

anyone know of an app that can detect these signals? Maybe decode them. easiest way to block them is to know they are there in the first place. i am suspicious that occasionally my laptop makes high pitch noise correlated to mouse movements when its running windows 10. edit:Thinking about it. seems possible that might actually be facebook. never installed their phone app untill i had android 6 because it wants mic pe…

You most probably have some "coil whine"[1]. It's very unlikely that you are hearing ultrasonic signals (disclaimer: I'm no expert). [1]: https://en.wikipedia.org/wiki/Coil_noise

sounded like "coil wine".

doesnt stop a phone app decoding it though. it was only when i moved the mouse. and came then went.

And i definately still have reasonable high frequency hearing. for example filing a complaint with Morisons in the UK for those high frequency speakers aimed at stoppping kids loitering. Don't know if they got rid of them or not because i stopped shopping there.

Re: “Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

#12

Post by erikbye »

ethbro wrote: post #2

I know it's Ars, but there has to be a better link with more detail than "here's a thing some people might be doing, somewhere."

The letter to the FTC has some more details.

https://cdt.org/files/2015/10/10.16.15-CDT-Cross-Device-Comm...

Re: “Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

#15

Post by mSparks »

erikbye wrote: post #9
mSparks wrote: post #6

anyone know of an app that can detect these signals? Maybe decode them. easiest way to block them is to know they are there in the first place. i am suspicious that occasionally my laptop makes high pitch noise correlated to mouse movements when its running windows 10. edit:Thinking about it. seems possible that might actually be facebook. never installed their phone app untill i had android 6 because it wants mic pe…

That is just electromagnetic interference.

It may have just been electrical interferance.

But electrical interfance from a trackpad? - made me suspicious at the time.

And one way or another, a proof of concept is only a few lines of javascript.

A very very easy way to link people in a room together.

And it would explain why the facebook app wants mic permissions when afaik it offers no audio features. it doesn't even need to be audio the maker of the app controls - just "fingerprint" sounds and report them back to facebook (or whoever).

Re: “Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

#16

Post by mirimir »

cooper12 wrote: post #10

Sorry but I found this to be very disappointing scarebait from Ars, who I expected to have higher standards. It doesn't explain how common this is yet the title makes it sound like it's super prevalent. (not to mention we're already being tracked in other ways that are worth worrying about more) It does a horrible job at explaining what's actually going on and why advertisers might use this instead of alternatives, i…

The key goal is cross-device tracking. Your phone vs your notebook vs your TV vs whatever else around has audio and net uplink.

Re: “Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

#17

Post by condiment »

mSparks wrote: post #6

anyone know of an app that can detect these signals? Maybe decode them. easiest way to block them is to know they are there in the first place. i am suspicious that occasionally my laptop makes high pitch noise correlated to mouse movements when its running windows 10. edit:Thinking about it. seems possible that might actually be facebook. never installed their phone app untill i had android 6 because it wants mic pe…

Your MacBook microphone can detect ultrasonic frequencies above 22khz, though I'm not sure whether my observed ceiling is an artifact of the microphone, or of the speaker I was using to emit the tones.

In my informal tests, most people are unable to hear any tone above 20khz or so. This is discovered, naturally, by starting with the highest pitch tone I can generate at the loudest volume, and lowering the pitch gradually until somebody covers their ears and starts screaming. This is usually the youngest person in the room.

You can generate and receive audio using web audio APIs. Creating a browser extension to detect ultrasonic comma would be fairly straightforward.

Re: “Ultrasonic cross-device tracking” embeds inaudible tones in advertisements

#20

Post by mSparks »

condiment wrote: post #17
mSparks wrote: post #6

anyone know of an app that can detect these signals? Maybe decode them. easiest way to block them is to know they are there in the first place. i am suspicious that occasionally my laptop makes high pitch noise correlated to mouse movements when its running windows 10. edit:Thinking about it. seems possible that might actually be facebook. never installed their phone app untill i had android 6 because it wants mic pe…

Your MacBook microphone can detect ultrasonic frequencies above 22khz, though I'm not sure whether my observed ceiling is an artifact of the microphone, or of the speaker I was using to emit the tones. In my informal tests, most people are unable to hear any tone above 20khz or so. This is discovered, naturally, by starting with the highest pitch tone I can generate at the loudest volume, and lowering the pitch gradu…

However, most audio output (at least back in the nineties and naughties) is not capable or creating sounds reliably above 16khz. They almost always have a low pass filter on which cuts it out. Apparently most dell laptop speakers cant even manage above 10khz

"You can't hear" doesn't have to be high frequencies though.

It can be more subtle like phase shifts and other "in audible range" fingerprinting.

While I've not used it for getting on 20 years now, I did do a lot of software audio engineering back in the day, everything from RF to DSP.

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