This kind of modulating data in infrasound or ultrasound is common, yes. It has been used in toys too, e.g. things that respond to certain sounds from a show. chibi-tech stuck some reverse engineered ultrasound triggers for a certain line of toys in some of her songs :)
Infrasound only works digitally because no speaker system can reproduce frequencies that low, and many analog systems will corrupt them (e.g. AC coupling). Ultrasound is therefore used most of the time in practice, but I believe infrasound has been used in digital song watermarking for DRM/copyright tracking purposes.
https://twitter.com/chibitech/status/1237326756672983040
Infrasound only works digitally because no speaker system can reproduce frequencies that low, and many analog systems will corrupt them (e.g. AC coupling). Ultrasound is therefore used most of the time in practice, but I believe infrasound has been used in digital song watermarking for DRM/copyright tracking purposes.