Huh, I wonder if it works if you play it over the PA system.

https://hackaday.com/2016/03/04/social-engineering-your-way-...

Edit: looks like an Ardunio can do this with PWM too

No. That won't work. It needs the electromagnetic / rf field. It can work if your phone is nearby becaause of the " parasitic EMF from your phone's speaker to "transmit" a similar code by playing a crafted audio file" according to the article and the DEFCON talk