Created by Zhang, John, last modified on Oct 27, 2020

Project Proposal - Haojiong Zhang (hz49 ECE120)

Project Proposal Guideline

  1. Introduction

It all started when I was watching a documentary on how Cambridge Analytica was able to influence the Brexit vote and the 2016 US presidential election through gathering mass data of individuals through analyzing their social media presence. I then considered the possibility of companies using the embedded microphones on your phones, laptops, smart-watches, the smart speakers, which can be easily accessed by apps. Though I know that there are more efficient ways of mass surveillance and most people aren't important enough to be subjected to this level of surveillance, I can’t help but notice the many times where I see some product pop-up on my feed right after I mention it in a conversation with a friend. Hence a (possibly stupid) idea was born.


  1. Statement of Purpose

The project aims to design a small and portable device that serves to jam out microphones in a 5-meter radius when placed. Ideally, it’s presence should not be noticeable to the user (e.i. no distracting noises).


  1. Background Research

So this is the basic layout of a dynamic microphone that’s embedded in your daily electric appliances. The microphone captures the sound waves with the diaphragm which vibrates in the same frequency. The metal coil around the magnet moves with the diaphragm to convert it into electric signals which are later processed.

                                                                                                                              

Given that the human auditory range and the range of most microphones is from 20Hz to 20kHz (0-130)dB, which sounds above 90 dB causing damage to the inner ear, the simple way is to create white noise to mask the user since the voiced speech of a typical adult male have frequencies from 85-180Hz and the range for women is from165-255Hz. The drawback being that the noise is audible. Another problem was that since we want to project to a five meter radius, multiple emitters are required, and two sound waves with the same frequency can superimpose and cancel each other


I was looking into a wearable microphone jammer by students at UChicago where they managed to address the problem of multiple emitters producing sound waves that cancel out each other through combining it with human motion. They also came up with using ultrasonic signals inaudible to the human which is able to “leak into the audible spectrum and produce a jamming signal inside the microphone circuit”.

It should be noted that many animals such as dogs and cats’ hearing range extends into the ultrasound. The top end for dogs is 45kHz and cats are 65kHz

  1. Design Details
  2. Block Diagram / Flow Chart


                                                                             



  1. System Overview

    I’m not very familiar with constructing Arduino boards, but I think it should just be an Arduino uno programmed with the range of frequency emitted from the transmitters and an on and off switch controlling the whole thing. This time adding a keypad and a digital display that allows me to change the emitted frequency. Since according to the paper their most effective frequency is around 25khz a 4 digit display should sufice. 
  2. Parts
           Four ultrasonic emitters 

                 One Arduino board

                 One toggle switch

                 A keypad

                 A 4 digit 7 segments digital display

                 A container of some sorts

  1. Possible Challenges

  • I think the main problem is how to stop the sound waves from different emitters canceling without having to wear the apparatus.
  • Going to have to brush up my Arduino skills.
  • Trying to find a reliable vendor that delivers to my region (China)


  1. References

"A Brief Guide To Microphones - What A Microphone Does". Audio-Technica.Com, 2020, https://www.audio-technica.com/en-us/support/a-brief-guide-to-microphones-what-a-microphone-does/.


" Chen, Yuxin, and Huying Li. "Understanding The Effectiveness Of Ultrasonic Microphone Jammer". Arxiv.Org, 2020, https://arxiv.org/pdf/1904.08490.pdf.


"Interactions With Sound Waves | Boundless Physics". Courses.Lumenlearning.Com, 2020, https://courses.lumenlearning.com/boundless-physics/chapter/interactions-with-sound-waves/.


Pujol, Rémy. "Journey Into The World Of Hearing - Specialists". Cochlea.Org, 2020, http://www.cochlea.org/en/hear/human-auditory-range.


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Comments:

The concept behind this is very interesting, but I think only having four ultrasonic sensors connected to an Arduino wouldn't be enough to satisfy the Honors requirement for this lab.

Could you perhaps add another part to this project, for example building an analog frequency generator circuit, building a microphone circuit to validate the effectiveness of your device, or some other type of logic circuit? Let me know if you need any other suggestions for ideas.
Posted by jamesw10 at Sep 22, 2020 19:59

So I was trying to figure out how to allow it to jam signals as well but unfortunately, signal jammers are illegal in both the China and US, so I was thinking of adding an RF detector because apparantly most bugs transmit data on that frequency, and some sort of screen or maybe just a led light for feedback. My only concern with that is radios and microwaves can mess up the reading? Also I wasn't quite sure what an analog frequency generator circuit is exactly? 
Posted by hz49 at Sep 27, 2020 00:46

Hi,

As James said, while the idea is very cool, the complexity is overall a bit low. We usually are looking for a project that has a bit more complexity than this.

I would echo James's suggestion. Building a second circuit that that emulates a "snooping microphone" to validate the effectiveness would be very cool and would qualify for honors credit. Also, by "analog frequency generator", he means an analog circuit that can generate a range of frequencies, based on some user input (like a knob, etc). Please revise.
Posted by fns2 at Sep 30, 2020 17:01