Some time ago I posted about a proof of concept style hack to use a computer's mic and speakers to bridge air-gapped computers and potentially defeat that layer of security. I recall that few thought much about the threat, and many even doubted that it existed.

Now this technology has been 'weaponized' by advertisers. PC World, ARS Technica

I'm taking this as notice of a new area of the spectrum being opened to intrusion and exploitation. You already can't have cameras in some secure locations. Any bets on how long till a kneejerk ban on 'audio devices' is proposed?

Dang. This has been real-world since 2015.

and

I wonder if there's any way to limit PC audio hardware to only the audible spectrum?

OK - decent news on this.

pcworld.com//security/ftc-warns-app-developers

1 - Android Only (so far)
2 - Not being used in the US
3 - FTC is not standing on the sidelines passively watching

a low-pass audio filter would seem to be the answer.