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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

#71

Post by danbruc »

mason55 wrote: post #65
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.

> 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.

People do this because they get some value like looking at cat pictures in exchange and to some extend certainly also because they misjudge the value they receive as compared to the value they give away. If you only track users and don't provide some value in exchange, then nobody should opt in. And the value probably also has to be immediate to some extend, just promising to provide better services in a year after analyzing the data will probably not convince many to opt in.

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

#72

Post by pklausler »

rfrank wrote: post #67
pklausler wrote: post #66

Earlier quoted context omitted.

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.

If your religion forbids saving or improving the lives of others with organs you're done with, please consider alternatives.

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

#73

Post by sandworm101 »

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??

>> How would a reasonable person not want to be an organ donor??

Because I have fundamental issues with the economics of organ donation. I do not want my organs used in million-dollar surgeries to save elderly rich people. I would much rather that money be spent more efficiently on younger/poorer people where it can save more lives. How many flu shots could be purchased for the cost of one heart transplant? I cannot change the economic realities of modern medicine, but the least I can do is not contribute my own flesh towards the problem.

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

#75

Post by ghurtado »

pklausler wrote: post #72
rfrank wrote: post #67

Earlier quoted context omitted.

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

If your religion forbids saving or improving the lives of others with organs you're done with, please consider alternatives.

Religion doesn't work that way. You don't go "Well, I have this set of values, so I think XYZ is the right religion for me". There are exceptions, but most of the time it's actually exactly the opposite.

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

#77

Post by Cyph0n »

blurbleblurble wrote: post #62
Cyph0n wrote: post #48

Earlier quoted context omitted.

> 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.

I am aware of the Nyquist rate. You're talking about very rare edge cases though. I believe the cut-off for an average young human is 20 kHz.

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

#78

Post by PeterisP »

Lagged2Death wrote: post #41
pasta wrote: post #3

Earlier quoted context omitted.

Take a look at Chirp: http://www.chirp.io/ Edit: In Firefox it seems this website is constantly playing audio. I think it is using a WebSocket to do this. Since I don't hear a thing I'm not sure what is going on here.

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…

Nowadays many standard cheap embedded audio chips included in phones and computers are capable of 92/96khz sample rate - so they can easily drive 40+khz ultrasonics.

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

#79

Post by M_Grey »

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.

I think this is good in a way, because it just reinforces what people are learning already: advertising is an "Us vs. Them" deal. They try to get to us, we try to block them.

A platform that doesn't let me block ads is a platform I won't use.

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

#80

Post by colanderman »

gugagore wrote: post #47
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…

I think that most people (not teenagers) cannot hear past 15 kHz, especially with other sounds playing. This is reproducible at standard sampling rates you mention. Harmonics are integer multiples of frequencies. Harmonics of an ultrasonic signal are even more ultrasonic. If there's any aliasing, those harmonics might map back to audible frequencies. However, no matter how cheap a speaker is, no aliasing happens. Per…

It's not necessarily a function of the speaker but of the low-pass filter on the output. Unfiltered samples played back at 48 kHz will mirror the audio content at 0-24 kHz to 48-24 kHz, and repeat that pattern at every 48 kHz multiple. (This is not quite exact because DACs emit step functions, not delta functions, and slew rate comes into play, but it is a rough approximation.) This happens even if the sampled signal is a sine wave.

So, any output stage after a DAC necessarily incorporates a low-pass filter to eliminate the aliasing artifacts. A cheap low-pass filter will allow these aliasing artifacts through. You can simulate this e.g. by digitally upsampling a, say, 8 kHz sampled signal to 48 kHz without any interpolation.

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