Sound that can bend itself through space, reaching only your ear in a crowd | Hacker News Reader

Sound that can bend itself through space, reaching only your ear in a crowd

theconversation.com

49 pointsamichail15 comments

Does it remind anyone of the targeted ads that John Anderton (Tom Cruise's character in Minority Report) hears when he moves through the city?

I've read an article about this in some German weekly paper when I was like 18?

Was hoping for this to come to fruition in a couple of year's time. But patience always wins, right?

I also remember reading about stationary ANC embedded in buildings at that time.

Unfortunately, the only magazine article from that time that I remember and that has become reality, is the one about identifying individuals in "anonymized" location traces, using very few data points.

Guess that's just the way things are...

The time I'm referencing are the late naughties.

This is clever engineering, but it's not sound that "bends itself" through space. The sound isn't changing direction in air - it's following paths created by the acoustic metasurfaces, and the audible sound is only generated at the intersection point of the two ultrasound beams.

Speakers that operate like this have been around for 30+ years under the name hypersonic sound. The original company “HSS” went under and/or pivoted to making Lrads. You can still occasionally find their speakers on ebay.

I bought one 16 years ago. It was pretty fun but definitely did not have the promised fidelity… the range and directivity was everything and more than it promised. We tested it out to a mile and could still hear it. Very cool.

So cool. Is this basically like 2 inaudible waves coming together in an "overlap spot" to create an audible moment?

Yes.

Since they are ultrasound waves, they are inaudible for humans, but they may be audible for various animals and for ultrasound detecting devices.

Yeah, the whole concept sounds to me like "let's fire a lot of high energy beams into a crowd, it will be fine".

I’m firmly convinced that a lot of the acoustic tricks that AirPods Pro do to achieve noise canceling involve ultrasonic harmonics, perhaps unintentionally - and this has created an epidemic of tinnitus among their users.

> and this has created an epidemic of tinnitus among their users

Excuse me, are there sources I can read more about this?

If there aren’t, please don’t spread the rumor. You might accidentally trick people into thinking it’s true.

Big claims require big evidence, and so far, this has none.

That’s exactly why I was asking for sources.

Big accusations require strong evidence. Please provide them, if you have them.

I'm not an expert. 99% of my “knowledge” about ultrasound is from the posted article. Your thought process around AirPods makes no sense to me.

I would be very surprised if active noise-canceling systems would produce sounds higher than 20KHz.

Which quantum operators can be found in [ultrasonic acoustic] wave convergences?

Surround sound systems must be calibrated in order to place the sweet spots of least cacophony.

There also exist ultrasonic scalpels that enable noninvasive subcutaneous surgical procedures that function by wave guiding to cause convergence.

"Functional ultrasound through the skull" (2025) https://news.ycombinator.com/item?id=42086408

"Neurosurgeon pioneers Alzheimer's, addiction treatments using ultrasound [video]" (2024) https://news.ycombinator.com/item?id=39556615

Interference patterns. Cool stuff. Made me think of the 3brown1blue video on holograms... that one blew my mind but that's par for the course for 3b1b...

This will definitely be used by all kinds of guru/magician types to demonstrate "telepathy" to their followers.

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