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New Sound May Ensure Privacy

posted by Fnord666 on Tuesday June 27 2017, @06:03PM   Printer-friendly
from the I-can't-hear-you-now dept.

Phoenix666 writes:

Most microphones are designed to emulate the human ear, hearing sounds that we hear, and not hearing ones that we don't. Scientists from the University of Illinois at Urbana-Champaign, however, have created a new sound that we can't hear but that is picked up by mics of all kinds. It could have some valuable applications, although there's also the potential for misuse.

The university's Coordinated Science Laboratory states that the sound is produced by combining multiple tones that interact with a microphone's mechanical workings, creating what is known as a "shadow" – this is a type of white noise that is detectable only by the microphone, as it's formed within the mic itself.

Transmitted by ultrasonic speakers within a room, the sound could be used to keep confidential conversations from being clearly picked up by hidden listening devices. The people talking would still have no problem hearing each other, as the sound would be inaudible to them.

It could also thwart illegal audio recordings in movie theaters or music venues, plus it could be used in place of Bluetooth for wireless communication between Internet of Things (IoT) devices.

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  • (Score: 0) by Anonymous Coward on Wednesday June 28 2017, @09:47PM

    by Anonymous Coward on Wednesday June 28 2017, @09:47PM (#532659)

    Unfortunately you've completely missed the point of their research. This has *nothing* to do with the mechanical, and even acoustic, properties of the microphone, and everything to do with the electrical properties. (namely the preamp and the LPF). They're squirting out inaudible ultrasonics which due to different nonlinearities in mikes and eardrums cause breating that is audible to one (the mike), but inaudible to the other (guess).

    How does the ultrasonic signal get to the LPF if it has *nothing* to do with the mechanical or acoustical properties of the mic? Mr Zobel long had the answer to the question of how to dampen filter ringing.

    there's enough information in the paper to reproduce their experiments. (as long as you have a sound source happy to produce 50 KHz.)

    I have a frequency generator which is enough to feed breadboarded tests with RC filters or negative transformer feedback. It doesn't matter though, as I already wrote - we can acoustically LP ultrasound at wavelengths of 8.5mm before it even enters the mic chamber.