Posted on 03/11/2018 7:31:13 AM PDT by grumpygresh
Bkmrk.
Very long time...
As to your comment regarding frequency range, most MEMs microphones have a response past 20KHz, and some even have a convenient resonant peak above 20KHz. Driving them with a very high SPL at that frequency causes them to clip sufficiently to prevent them from responding to audio inputs.
If you want to watch this kind of interference get a piezo driver and generate a high SPL field -- dangerously high, like 140 dbM, and see what the output of your mic looks like. Unless you have a very slow response dynamic mic, you are likely to see hard clipping of the mic output. And actually the only thing that saves the dynamic mic is its poor high frequency response.
I saw a Rockford episode where Rockford discovers a ex FBI agent has wiretapped several people including his father using physical microphones planted at the location.
He just dialed a number for the bug and listened in.
That show was 40+ years ago.
Today the wiretap is not in your home but in some telephone exchange. You would have no idea you were being bugged.
Only way to block is use tin foil over your telephones and now the smart tv and laptops with cameras built in. Then there is the tracking of where you have been on the internet and the searches you do like voice jammers to block recording of conversations? What about microphone detectors etc.
That caused a red light to start blinking and the FBI and NSA are now listening in and watching what you are typing.
So good luck and look out for black helicopters and black SUVs following you and a van down the street parked in the same spot for days : )
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