I listen to some talk radio stations via Internet, because the reception is better. I live in a semi-rural town and it is difficult to get over-the-air TV and radio.
I use a program called Radio Sure to access radio stations.
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I have noticed recently that one area talk radio station frequently goes silent during commercial breaks. I assume they cannot sell enough advertising to fill the breaks. I also wonder how much longer they will survive.
A radio station can broadcast commercials that they produce, and that they hold the full broadcast rights to. Commercials sold by national conglomerates are not allowed to be broadcast over the web - very hard to get listener numbers that translate into sales revenue.
No different than listening to Rush online.