● HD Radio
What about HD Radio?
"HD Radio" is iBiquity Digital Corporation's trademarked name for their digital audio broadcasting technology. One would think that like TV, HD would stand for High Definition. However when HD Radio was first introduced the HD stood for Hybrid-Digital. But now Ibiquity has said that they have decided that the "HD" in "HD Radio" stands for nothing. In any case HD Radio is lossy compressed digital radio broadcasting—and typical bitrates are 100, 112, 125, or 150 kbit/s of lossy data.
If the FCC discontinues analog simulcasting, each station will have over 300 kbit/s bandwidth available, which could all be used for one channel at a higher bitrate and level of sound quality—or the bandwidth could be divided into several channels such that each channel would be at a lower bitrate / level of sound quality. However there is also the provision for a "fall back" condition where it reverts to a more robust but far lower quality 25 kbit/s signal. Of course this makes it important to have a good signal from your antenna.
NOTE: If you would like to see where the HD Radio stations are in your area here is a link.