I slightly agree. However, these days it seems more and more that "thing elite spy agency does to track terrorist" is on about a 6 months to 1 year lead on "thing startup does to target ads."

Wouldn’t even surprise me if it was the other way around either.

Some of the brightest minds of this generation are working on ad tech.

Sadly.

Angelheaded hipsters burning for the ancient heavenly connection to the starry dynamo in the machinery of night, indeed.

Interesting thanks

Sorry here is the source:

https://www.bleepingcomputer.com/news/security/ultrasound-tr...

It appears to have happened already

Wow, now 44.1kHz sound cards should be very desirable

> A team of researchers from the Brunswick Technical University in Germany discovered [234] Android apps that employ ultrasonic tracking beacons to track users and their nearby environment.

https://en.wikipedia.org/wiki/SilverPush

My tinfoil hat is spinning!

Ability and motive...

Are they able to do this? Yes, for sure.

Are they willing to this? For terrorists or maffia bosses, no doubt. For smaller fish? Maybe they can't be bothered. Or maybe they can.

Once it's productized, it's probably easy to reuse.

Technically, but maybe not bureaucratically.