As a child, I used walkie talkies a lot on certain adventures. I was always confused by the fact that I could hear a friend on one station, but never another if we both weren't on the same one. As I got older, I learned that these stations were in fact frequencies, and anyone within range on that some frequency could receive or transmit messages from or to me. These devices, however, cannot receive or transmit messages at the same time. The same thought process goes for radios, it seems as well. The different frequencies transmit different sounds to cars, radios, etc. The sounds are perceived as different stations, relative to a certain area, like 98PXY or Warm 101.3.