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Recognizing Speech from Smartphone Gyroscopes (2014)

crypto.stanford.edu

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Re: Recognizing Speech from Smartphone Gyroscopes (2014)

#11

Post by wallacoloo »

leni536 wrote: post #10

Solution: low pass filter gyroscope sensor data before the application can access it. Is there a legitimate reason for an application to need gyroscope data in the range of ~200Hz?

I think this is a legitimate usage for some games, for example, racing games in which you steer via tilt. The bigger issue in this case is not the frequencies visible to the application (the relevant hand motion is much below 200 Hz), but rather the latency of these movements. If possible, a game should be able to respond to a tilt action within the duration of a single frame.

But it's impossible to filter a signal in the time domain without introducing a phase shift (i.e. a delay). As a result, you cannot remove that extra frequency information before sending the data to an application without making sacrifices on latency.

Re: Recognizing Speech from Smartphone Gyroscopes (2014)

#13

Post by leni536 »

wallacoloo wrote: post #11
leni536 wrote: post #10

Solution: low pass filter gyroscope sensor data before the application can access it. Is there a legitimate reason for an application to need gyroscope data in the range of ~200Hz?

I think this is a legitimate usage for some games, for example, racing games in which you steer via tilt. The bigger issue in this case is not the frequencies visible to the application (the relevant hand motion is much below 200 Hz), but rather the latency of these movements. If possible, a game should be able to respond to a tilt action within the duration of a single frame. But it's impossible to filter a signal i…

Alternative solution: make the unfiltered gyro data available through an explicit permission.

Re: Recognizing Speech from Smartphone Gyroscopes (2014)

#14

Post by blincoln »

boxstream wrote: post #5
johansch wrote: post #4

Earlier quoted context omitted.

Chrome on Android shows the proper data - with no special permissions or warnings. It updates at ~57 samples/s.

If you check the paper the authors indeed mention some rate limitations using Chrome. However Firefox provides samples at 200 Hz. Also, every application can access those measurements without any permissions.

As the authors note in the full paper, even a sample rate of 200 Hz only results in capturing audio information for frequencies up to 100 Hz.

If one applies a 100 Hz filter to some samples of human speech (even low-pitched male voices, as the authors of the paper suggest), the result is (unsurprisingly) the sort of "womp womp" that one might expect to hear from a car with giant subwoofers, not anything containing recognizable words.

The authors of the paper admit that they were unable to recover the content of speech, but focused on identifying the speaker. That's a long way from capturing credit card numbers (which is what their promo video implies).

Basically, I'll believe it when I see it. The approach is really interesting, though, and I think could be useful for other things.

Re: Recognizing Speech from Smartphone Gyroscopes (2014)

#15

Post by wallacoloo »

leni536 wrote: post #13
wallacoloo wrote: post #11

Earlier quoted context omitted.

I think this is a legitimate usage for some games, for example, racing games in which you steer via tilt. The bigger issue in this case is not the frequencies visible to the application (the relevant hand motion is much below 200 Hz), but rather the latency of these movements. If possible, a game should be able to respond to a tilt action within the duration of a single frame. But it's impossible to filter a signal i…

Alternative solution: make the unfiltered gyro data available through an explicit permission.

Perhaps it's possible to use some sort of active cancellation - like what noise-cancelling headphones do - only in this case you would be trying to minimize the correlation between gyroscopic data & microphone data.
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