back to article Boffins shake up smartphone with motion-sensor as microphone

University of Illinois boffins have proved that someone who steals your phone can perform hardware hacks on it. As a maker-hack, The Register can't help but admire the work done to create the “VibraPhone” (even the pun is better than average). As a security vulnerability, we'll file this under “if you lose your phone, you're …

  1. lglethal Silver badge


    Clever boffins. I imagine someone in one of the phone companies (or all of them!) is now going off to see if a) they can turn a regular mic into a vibration sensor or b) a vibration sensor into a mic. One less component in your phone is almost always a good thing (less failure, cost, weight, etc.)

    Here's a Beer for those Boffins!

    1. Anonymous Coward
      Anonymous Coward

      Re: Clever

      Too late, some microphones already use MEMS devices that are essentially this.

  2. Anonymous Coward
    Anonymous Coward

    So which is it

    The text talks about a vibration sensor, but all the pictures reference vibration motors.

    I didn't think phones had specific vibration sensors, but collected motion data from accelerometers (which would not have the sampling rate for audio).

    It sounds more like they're using the motor as a sensor, via an ADC... that's clever on the scale of "interesting, but completely pointless"

    1. Anonymous Coward
      Anonymous Coward

      Re: So which is it

      Thanks for asking that. I was confused too.

      To me a sensor is something that responds to some environmental condition in some way.

      The vibration *motor* is NOT a sensor - even though it appears to be being adapter to work as such here.

      Agree with other poster - interesting but pointless.

      1. Hero Protagonist

        Re: So which is it

        And the headline is even more misleading, mentioning a motion sensor which is an actual thing on a phone but is NOT what they used. Sloppy article all around.

  3. RatX

    In other news, "researchers" have found a way of stealthily using a smartphone's light sensor as a 1x1 pixel monochrome spy cam! Provided they're given unrestricted physical access to your phone for a few hours in their lab... I'm reasonably sure there are much greater threats to our privacy we need to be made aware of than this twaddle.

  4. A K Stiles


    Interesting idea, however useful it ultimately ends up being. The main part of their research actually seems to be about regenerating the 'missing' frequencies from the vibration-motor-as-microphone signal rather than the hardware hacking to enable it's use. I notice that their sample voice is quite deep so probably plays to the strengths of the experiment. I wonder how effective it is for a less resonant, higher pitched voice?

  5. Justthefacts

    Useful if combined with other stuff

    What they've *actually* shown is that they can recover speech, specifically, from a very noisy signal (same as quiet) that is heavily band-limited way below what you'd expect, and non-linearly distorted. There's other covert sensors that can give you exactly that input.

    There's a couple of very nice papers that experimentally demonstrate moderate sound recovery from smartphone video imagery through windows, of objects within the room. The principle is that something like a Coke can vibrates very slightly, and the straight lines on the object appear very slightly wavy due to camera sequential scan.

    This research might improve the speech recovery from such a system - which if you listen to it, is at the level of hearing some syllables and moderately guessing others with more high-frequency components.

  6. Prst. V.Jeltz Silver badge

    whats a vibration sensor and why does a smartphone need one?

    for earthquake prediction apps?

  7. Cynic_999 Silver badge

    If you have the access and ability to do such extensive modifications, why no simply add a small microphone to the phone?

  8. Rol Silver badge

    Steal phone, mess with it for hours, put it back without anyone realising.


    Steal phone, swap all the cards and what have you into an already prepared identical phone, put it back a few minutes later.

  9. Anonymous Coward
    Anonymous Coward

    If you can use the vibration motor as a sensor

    Can't you simply use the microphone? Sure, there are permissions governing the microphone, but how many apps have legitimate access to already? And how many apps will be installed on Android that require the permission even though they don't need it?

    The difference between "install an app that uses the vibration motor as a sensor/microphone" and "install an app that uses the microphone" is not worth defending. This is like trying to caulk a hairline crack in your home next to an open window that can't be closed.

  10. Neoc

    "University of Illinois boffins have proved that someone who steals your phone can perform hardware hacks on it"

    This must be the biggest "well, duh - how else are they gonna perform hardware hacks" statement.

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