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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

#61

Post by WebIsSadWithTor »

mSparks wrote: post #20
condiment wrote: post #17

Earlier quoted context omitted.

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…

I think you're making a key point. If the goal was to measure physical proximity then radio signals could be used and would probably be more reliable. However, if you want to check if a user can actually hear something - like an audio ad or videos+audio - using audio makes perfect sense and in this case you can just add an inaudible fingerprint to the existing audio.

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

#62

Post by blurbleblurble »

Cyph0n wrote: post #48
Lagged2Death wrote: post #41

Earlier quoted context omitted.

Since I don't hear a thing I'm not sure what is going on here. Click on the gem and the web page will play a "chirp," which is loud and beepy and not ultrasonic or secret at all. It's an analog modem type system, except probably way slower than 300 or even 110 baud. Everything old is new again, I guess. In any case, the point is: the Chirp system is distinct from the supposedly-possible secret systems the Ars story i…

> If a computer's audio drivers and audio hardware are set up to play back at standard CD/DVD sample rates (44KHz or 48KHz), then ultrasonics are not happening there, period. The same principle applies to inputs. What do you mean? All you need to do is sample the received audio at 44.1 kHz. Android at least has a low-level API which allows you to customize sampling rate.

According to Nyquist's work, you need a sample rate of 2f to represent a frequency f.

So with 44.1 kHz you could only represent audio up to 22 kHz. There are kids who can hear at these frequencies.

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

#63

Post by [deleted] »

Cyph0n wrote: post #48
Lagged2Death wrote: post #41

Earlier quoted context omitted.

Since I don't hear a thing I'm not sure what is going on here. Click on the gem and the web page will play a "chirp," which is loud and beepy and not ultrasonic or secret at all. It's an analog modem type system, except probably way slower than 300 or even 110 baud. Everything old is new again, I guess. In any case, the point is: the Chirp system is distinct from the supposedly-possible secret systems the Ars story i…

> If a computer's audio drivers and audio hardware are set up to play back at standard CD/DVD sample rates (44KHz or 48KHz), then ultrasonics are not happening there, period. The same principle applies to inputs. What do you mean? All you need to do is sample the received audio at 44.1 kHz. Android at least has a low-level API which allows you to customize sampling rate.

[deleted]

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

#64

Post by [deleted] »

Cyph0n wrote: post #48
Lagged2Death wrote: post #41

Earlier quoted context omitted.

Since I don't hear a thing I'm not sure what is going on here. Click on the gem and the web page will play a "chirp," which is loud and beepy and not ultrasonic or secret at all. It's an analog modem type system, except probably way slower than 300 or even 110 baud. Everything old is new again, I guess. In any case, the point is: the Chirp system is distinct from the supposedly-possible secret systems the Ars story i…

> If a computer's audio drivers and audio hardware are set up to play back at standard CD/DVD sample rates (44KHz or 48KHz), then ultrasonics are not happening there, period. The same principle applies to inputs. What do you mean? All you need to do is sample the received audio at 44.1 kHz. Android at least has a low-level API which allows you to customize sampling rate.

[deleted]

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

#65

Post by mason55 »

Analemma_ wrote: post #60
rocky1138 wrote: post #57

Earlier quoted context omitted.

I found it interesting that the FCC's recommendation was to build an opt-out system, since this is so obviously anti-human and pro-corporation. It shows where their interests lie. This kind of system should be opt-in only, with hand-signed agreements.

Exactly. Opt-out systems are fine for things like organ donation, because a reasonable person could go either way. Building an opt-out system that no one in their right mind would ever opt into just reeks of anti-consumer behavior trying to hide behind a polite face.

> Building an opt-out system that no one in their right mind would ever opt into just reeks of anti-consumer behavior trying to hide behind a polite face.

What system are you referring to? If the system is "opt in to being tracked if you want to read this/use this service for free" then plenty of people would opt in. Look at Facebook.

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

#66

Post by pklausler »

Analemma_ wrote: post #60
rocky1138 wrote: post #57

Earlier quoted context omitted.

I found it interesting that the FCC's recommendation was to build an opt-out system, since this is so obviously anti-human and pro-corporation. It shows where their interests lie. This kind of system should be opt-in only, with hand-signed agreements.

Exactly. Opt-out systems are fine for things like organ donation, because a reasonable person could go either way. Building an opt-out system that no one in their right mind would ever opt into just reeks of anti-consumer behavior trying to hide behind a polite face.

Whoa, wait a sec there with your example. How would a reasonable person not want to be an organ donor??

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

#67

Post by rfrank »

pklausler wrote: post #66
Analemma_ wrote: post #60

Earlier quoted context omitted.

Exactly. Opt-out systems are fine for things like organ donation, because a reasonable person could go either way. Building an opt-out system that no one in their right mind would ever opt into just reeks of anti-consumer behavior trying to hide behind a polite face.

Whoa, wait a sec there with your example. How would a reasonable person not want to be an organ donor??

Religious reasons, family not wanting that to happen, etc.

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

#68

Post by Analemma_ »

pklausler wrote: post #66
Analemma_ wrote: post #60

Earlier quoted context omitted.

Exactly. Opt-out systems are fine for things like organ donation, because a reasonable person could go either way. Building an opt-out system that no one in their right mind would ever opt into just reeks of anti-consumer behavior trying to hide behind a polite face.

Whoa, wait a sec there with your example. How would a reasonable person not want to be an organ donor??

There is a theory that organ donors get worse medical attention and have higher mortality rates in hospitals. From what I've seen it doesn't hold up well against the evidence, but it's still within the bounds of what I'd call "reasonable disagreement".

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

#69

Post by ogig »

danbruc wrote: post #46

This is reaching the point where the only sensible policy is to flat-out prohibit all forms of adverting on any medium. Paying a company to lie to you is already a pretty bizarre idea but the invasion of privacy - online or offline - makes advertising increasingly intolerable.

Child oriented ads are especially awful. We let some greedy people massively influence our kids just so they profit. I would ban every kind of marketing oriented to kids and youngs.

If you have something really useful and good for the kids, sell it to their fathers. If you want to scam their money then get out.

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

#70

Post by maxerickson »

sathackr wrote: post #39
mgr86 wrote: post #37

Earlier quoted context omitted.

I wish I knew what those apps were. Or what signs I can look for. I generally don't have many "garbage" apps on my phone, but I've always suspected it with words with friends--Yes, my gf have been playing that game together since we started dating 5 years ago. Every so often an Ad will come on and the volume all of a sudden adjusts itself from mute to about 33%. Its distributing that an advertisement can have that po…

I think it's an app specifically installed for the purpose. I just asked him what it was called, he said it was an Arbitron(now owned by Nielson) device. I googled Arbitron device and found this: https://en.m.wikipedia.org/wiki/Portable_People_Meter

Note that it doesn't use ultrasound, it embeds information in the normal audio in a way that humans are not likely to perceive (psychoacoustic masking).
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