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Comment by roenxi | Hacker News Reader

Article says:

> Another cool use of low power, always-on DSPs is using ultrasound sonar to detect humans. AMD’s ultrasound runs at above 20 KHz but below 35 KHz, letting it get through the microphone and speaker’s band pass filters. Then, it can use Doppler shift to distinguish human movement from static objects in the same way that a look-down radar filters out ground clutter.

This chip sounds pretty creepy, although I doubt it'll be possible to escape from this sort of thing. The US spies will be loving these feature trends.

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This will be torture for dogs. I is like a 5 kHz tone for humans.

All laptops with a 5 kHz tone would be returned as defective. In the 90's harddrives often had a 7200 Hz whine which was enourmously annoying. Todays harddrives are silent compared to the old ones.

I agree it could be torture for all sorts of creatures, including small humans.

But whether anything is bothered by the sound depends on the energy level and other characteristics. Spread spectrum ultrasound sonar below the local noise floor may be technically feasible, though perhaps not with regular laptop speakers and audio circuitry.

Dogs survived CRT monitors and TVs, so I'd assume their behaviour would be known in that instance.

I'm unlucky enough to hear 15 kHz, and you'd easily hear any TVs turned on two storeys away. CRT ultrasounds used to be unbearably, migraine-inducing loud.

I assume laptop speakers wouldn't be anywhere as bad.

Triggered. The 15 kHz whine was so pervasive that watching or listening to studio shows, CRTs within the studio could still be heard.

> In the 90's harddrives often had a 7200 Hz whine which was enourmously annoying.

The what now ? nothing in hard drive runs at that frequency

More like 7200 RPM, but that would be 120Hz. The motor would be driven by PWM though, that's more likely to cause sound issues

A deep dive into that topic...PWM drivers for hard drives, torque ripple, and reducing noise. https://www.ti.com/sc/docs/msp/papers/1998/bwhite.pdf

I was just reading about the use of this and the company it looks like these are from (mobile so I don't have the name handy but it looks like Lenovo T14 g4 uses it) one of the "features" is to auto lock the machine and another is for auto monitor finding so it can lay out the desktop magically based on where it thinks monitors are to the laptop. Kinda neat. I'm not sure how it'll work for most offices based on the demos though. It looked like it could just decide if a monitor was right or left but most monitors are above AND right/left on mounts.

Now your Windows laptop can frustrate both humans and canines

Reminds me of BadBIOS, a little bit

Microphone on the chip or via an attached peripheral?

Almost certainly attached peripheral.

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