Slashdot Mirror

← Back to Stories (view on slashdot.org)

Ad Networks Using Inaudible Sound To Link Phones, Tablets and Other Devices (arstechnica.com)

Posted by timothy on from the high-keening-wail dept.

ourlovecanlastforeve writes with a link to Ars Technica's report of a new way for ads to narrow in on their target: high-pitched sounds that can make ad tracking cross devices and contexts. From the article: The ultrasonic pitches are embedded into TV commercials or are played when a user encounters an ad displayed in a computer browser. While the sound can't be heard by the human ear, nearby tablets and smartphones can detect it. When they do, browser cookies can now pair a single user to multiple devices and keep track of what TV commercials the person sees, how long the person watches the ads, and whether the person acts on the ads by doing a Web search or buying a product.

6 of 223 comments (clear)

  1. Microphone access. by Noah+Haders · · Score: 5, Insightful

    And why can a rogue website or app access the microphone? Oh yeah cuz android.

    1. Re:Microphone access. by Solandri · · Score: 3, Insightful

      Starting with Marshmallow, you can disable microphone access on an app-by-app basis.

    2. Re:Microphone access. by Anonymous Coward · · Score: 5, Insightful

      Phones and speakers cover frequencies beyond human hearing because they're physical objects. Making something that can record 16kHz with good fidelity but won't record 20kHz at all would actually be quite difficult. Did you know that some lossy audio codecs apply a 16kHz low pass filter to the audio signal? No? If that cutoff removed frequencies which many people can hear, everybody would know about it. Youtube does that, btw. In practice there are few people beyond their teenage years who can hear tones above 16kHz unless they're very loud, and even most teenagers can not hear 19kHz or higher. But the microphones in phones and tablets have no trouble picking that up.

  2. First... BULLSHIT by Anonymous Coward · · Score: 3, Insightful

    1. Mics don't pick up ultrasonic
    2. Speakers don't reproduce ultrasonic
    3. And even if these somehow did, Nyquist already limits it all

    Look at a high-end mic's response curve. Most barely get above 16 kHz, after which they drop off very fast. Compare that to any system that may be attached to a computer. Same for a loudspeaker. High-freqs are directional, meaning if you get off-axis even a little, even more drop-off. All BULLSHIT. The internet at play and the eager ignorants ready to believe anything it proclaims.

  3. It's also rather hard to believe it would work by Sycraft-fu · · Score: 5, Insightful

    Ultrasonic response is not something most devices are good at. We, unsurprisingly, tend to design your sound systems around what we can hear. Particularly when you are talking cheaper equipment the high frequency response of speakers and microphones is often not very impressive. There's also the issue that the digital audio compression we use for things, like TV broadcasts, deemphasizes high frequencies.

    So for this to work they need:

    1) A TV broadcast with sufficient audio bitrate to get their high frequency signal encoded (the AC-3 streams usually used in ATSC broadcasts can be any bitrate from 64kbps to 448kbps).

    2) Encoded in such a way by the broadcaster that the high frequencies are preserved to a sufficient amount that their signal isn't distorted.

    3) Reproduced by speakers good enough to produce their signal, but to do it at a sufficient level to be picked up (speakers roll off at more extreme frequencies).

    4) Picked up by a microphone with sufficient range to be able to receive such a signal and isn't being occluded too much be being in a pocket or something.

    5) Processed by a program running on the device, that has control of the microphone at the time the signal is playing.

    Ya... While that isn't impossible, that is not likely to work any real amount of time. To have any good chance of working you'd probably have to push the signal down in to the audible range, which would of course piss people off to hear spurious high frequency noise. Likewise for it to be of any use the user would need to have an app on their device that is running. The mic doesn't magically record everything that comes in and store it for anything to access. A program has to be running and take control of the microphone to be able to get any input from it.

    This sounds like an advertiser pipe dream, not something that has been tried with real technology in realistic settings.

    People seem to think that ultrasonic communication is some kind of magic. It isn't. I mean it can be done, no question, you can encode information in sound, and you can do it in sound frequencies above human hearing. However that doesn't mean you can do it with any arbitrary device, or under arbitrary conditions.

  4. Re:Super Duper Boy Scout Best Behavior by nukenerd · · Score: 4, Insightful

    And even when the button is actually a switch with an air gap, the push-on push-off type, you cannot see if it is on or off. With old-time toggle switches (and rocker switches, though less obviously) you could see at a glance if it were on or off.

    Last night I wasted ten minutes trying to connect my laptop to my WiFi before realising that its "Kill" button was in the "Kill" state. It does have a light in the button to show if connected, but that is not the same as being un-killed - ie the light stays off if the problem is at the wireless hub or you are out of range.

    Designers (ie the art graduate types) prefer buttons because they believe their design to be the absolute optimum aesthetic. They therefore do not want the visual distubance that would result from a toggle or rocker switch being moved into a different position. That is the way they think.