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> If a computer's audio drivers and audio hardware are set up to play back at standard CD/DVD sample rates (44KHz or 48KHz), then ultrasonics are not happening
by Cyph0n 10y ago
> If a computer's audio drivers and audio hardware are set up to play back at standard CD/DVD sample rates (44KHz or 48KHz), then ultrasonics are not happening there, period. The same principle applies to inputs.
What do you mean? All you need to do is sample the received audio at 44.1 kHz. Android at least has a low-level API which allows you to customize sampling rate.
- macawfish 10y agoAccording to Nyquist's work, you need a sample rate of 2f to represent a frequency f. So with 44.1 kHz you could only represent audio up to 22 kHz. There are kids who can hear at these frequencies.
- Cyph0n 10y agoI am aware of the Nyquist rate. You're talking about very rare edge cases though. I believe the cut-off for an average young human is 20 kHz.
- macawfish 10y agoYeah, I get that, just saying, if we are going to worry about people with disabilities, I believe that we should care about the psychoacoustic wellbeing of "edge case" humans who can hear ultrasonic tones.
- Cyph0n 10y agoSo you're comparing disabilities, like not being able to walk or see, to a slightly annoying tone? Of course, it also depends on the estimated number of "edge cases" out there.
- colanderman 10y agoAnd even then, you need a few kHz bandwidth for the low-pass filter. Those high frequencies are greatly attenuated.
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