There isn't very much to add about this day other than it was 48 years ago.
Here is a tape I recently found covering the entire day as broadcast by KNX-AM in Los Angeles from approximately 10:45am (PST) until a little after noon. In technical terms, this is what was known as a Logtape - recordings of a broadcast day made by a radio station according to FCC regulations at the time. The speed is horribly slow in order to accommodate 24 hours, so the sound quality of this recording is a little sketchy, even with a lot of work going into it. Remember, it's history.
I purposely left an extended excerpt of The Arthur Godfrey Show in to illustrate how completely unremarkable that day was at first, and to give you some idea of how the shock unfolded in real time, when even at first the station switched back to its regular programming as if not knowing what to say or how to react to what it was getting over the wires.
So about 14 minutes in the bulletins start, cutting Arthur Godfrey off who was pre-recorded three hours earlier. And then, after some confusion, the rest of the time is taken up with the events as the news flashed in from Dallas.
Like I said, there really isn't much to add that hasn't already been written, debated and pored over in the last 48 years.
Sometimes it's best just to let the sounds speak for themselves. And imagine you're hearing it for the first time.