Don't forget a *lot* of big market PPM encoded stations are reported with single line reporting. As far as I can tell this includes all iHeart stations. So with the public numbers on those, we have no idea how much share and cume is coming from the stream.My take is that Nielsen isn't set up to really count people listening to radio online. The stations themselves can see actual usage numbers from their ISPs. That's the number SoundExchange uses to charge royalties, not Nielsen. What we're seeing is a big difference between those public numbers and what stations see internally.
Check for stations that are combined here: Simulcast Total Line Reporting