Kind of like a reverse Portable People Meter: https://en.wikipedia.org/wiki/Nielsen_Audio#Portable_People_Meter https://en.wikipedia.org/wiki/Nielsen_Audio#Port

Kind of like a reverse Portable People Meter: https://en.wikipedia.org/wiki/Nielsen_Audio#Portable_People_Meter https://en.wikipedia.org/wiki/Nielsen_Audio#Portable_People_...