Researchers at Penn State invented hypertargetable audio that doesn’t require any equipment to be worn by the receiver https://futurism.com/sound-audible-enclaves

It’s easy to jump to military applications for this (disguise the sound of gunfire! confuse and manipulate your enemy!) but I think it’s more likely it gets used for advertising first

The Farcaster formerly known as Kchamp. Books, beats, bodybuilding, bright ideas and beautiful things.

katherinechampagne.com

Seems like headphones will be required absolutely everywhere, time to learn sign language ig

Maybe some expensive subscriptions to opt out of aural advertisement assault? This tech in Vegas would be wild. 
One could really mess with someone (or a population) with this kinda thing