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I'm currently toying with making an "air" MIDI controller that uses ultrasonic distance sensors (HC SR04). Those sensors work around 40kHz, well beyond normal

by bambax 6y ago

I'm currently toying with making an "air" MIDI controller that uses ultrasonic distance sensors (HC SR04). Those sensors work around 40kHz, well beyond normal human hearing (human range is 20Hz to 20kHz and narrows with age) and I certainly don't hear anything. Yet my children, who are between 10-15, swear they can hear them (and I have at least verified they can tell by ear when they are on or off). I wonder how an array of 256 of these would sound to them? (From the product image: 16x16=256).

deleted 6y ago
[deleted]
codezero 6y ago
I suspect they could be hearing echos that fall into a lower frequency outside of your hearing band.
- bambax 6y ago
  Yes it's impossible they are hearing anything at 40kHz. Either the generated sounds are not really 40kHz, or there is something vibrating or resonating that produces something they can hear. But the question about running 256 of those simultaneously remains.
  - codezero 6y ago
    Absolutely!