4 ms·
The frequency response of most microphones (before DSP filtering) does not perfectly cut-off above 20 khz. I suppose if you were really paranoid you could walk
by alva 10y ago
The frequency response of most microphones (before DSP filtering) does not perfectly cut-off above 20 khz. I suppose if you were really paranoid you could walk around blasting exceptionally loud noise around and above this freq for privacy ;). Although your local dogs might not be too happy
- bigiain 10y agoHeh! Finally a profitable pivot idea for uBeam! Get their ultrasound transmitters mounted in hats or sunglasses, instant "privacy shield"! ;-) (Bug report #0000001: "I charged my iPhone up by carefully holding it within 8 inches of my uBean transducer all night then when I went to make a call in the morning with my uBeam Privacy Sunglasses(tm) on, the other party couldn't hear anything I said." Response: "Closed WONTFIX. You're holding it wrong.")
- napoleond 10y agoI realize I'm being a stereotypical message board nerd about what was presumably a joke, but: I don't understand what you're proposing. Surely the extraneous frequencies could just be filtered out at playback? Or ignored entirely, since--as you imply--human ears filter that out anyway.
- simcop2387 10y agoIf they've got any kind of dynamic gain going on so that they can capture the quietest stuff when nothing's going on but not clip everything when it's louder then they might not be able to do that. Once it's recorded only the information they sampled will be there. So if you play something really loud that's not hearable by a human but is by the recorder and it changes the gain so that it can record it properly then it can miss anything quieter than the noise. White noise above 20kHz would be perfect for this since it would also alias down to lower frequencies with a badly designed setup.