they're affected listening to the raw microphone capture. that's because the noise generated is much louder than the speech. so listening to raw microphone capture with this thing on, you can't make out words at all - just a few syllables here and there. the key is that the full voice signal is still captured by the microphone. you then filter out the additional noise (your conference software and laptop microphone does that at a shitty level, rtx voice is the top consumer product for this). once the noise is gone, you have only the original voice. due to the filtering, the original voice is very lightly garbled, which is enough to confuse voice recognition software, not your ears.
notice how they're using voice recognition to measure success? that's misleading and on purpose. if they used a person to see if this product is effective, the result would be - the product is literally nothing but a loud noisemaker which in zero ways does what it says it does.
now, I don't have an rtx. if you want to screw around, here's a very shitty two megabyte software version of what rtx voice does, it's open source and just a couple of meg. https://antlionaudio.com/blogs/news/free-active-noise-suppre...
a low pass filter, or a nice microphone would not help you at all here - the white noise is in the vocal range and no simple frequency filter is going to remove it. their product makes ultrasonic noise, which (probably due to microphone resonance) makes the mic vibrate in the audible range. again, not affecting the original voice signal, so it's loud white noise overlaid on top of the voice.
it does seem putting something in front of the mic that absorbs ultrasonic frequency but not lower voice frequencies works well to block this. which is why the thin plastic waterproofing film over the phone microphone completely blocks this product - no noise removal filter needed.
So literally any smartphone with water resistance bypasses this thing and records fine. for the rest, just run a noise removal filter on the recording and listen to it. for governments, I'm sure their spy mics are waterproof and immune, and if not, their voice recognition is better than whatever consumer tech these guys tested it on.
Well, of course.
But I was talking about listening directly, not via a microphone.
The whole point of the device that the white noise is not evident to listeners in the vicinity. If it was, people would not be able to speak to each other.
Which means that it's caused by intermodulation in the crappy microphone. Therefore a better quality mike (and a LPF) would remove it.